GSM - Global System for Mobile Communications (2G)

What is GSM?

  • GSM (Global System for Mobile Communications) is a standard developed to describe protocols for second-generation (2G) digital cellular networks. It enables voice calls, SMS, and limited data services using circuit-switched technology.

  • GSM defines how mobile phones communicate with base stations and the core network using a layered protocol stack.

Why is GSM useful?

  • GSM revolutionized mobile communication by offering: * Global interoperability – Used in over 200 countries. * Secure voice and text – With built-in encryption and authentication. * Efficient spectrum use – Through TDMA and frequency reuse. * Roaming support – Seamless service across networks and countries. * Foundation for 2G/3G/4G evolution – GSM laid the groundwork for modern mobile networks.

How it works?

  • Mobile Registration – The phone connects to the nearest base station and authenticates with the network.

  • Call Setup – The MSC (Mobile Switching Center) routes the call using signaling protocols.

  • Voice/Data Transmission – Voice is digitized, encrypted, and transmitted over the air.

  • Call Termination – The session ends and resources are released.

Where is GSM used?

  • 2G mobile networks – For voice and SMS.

  • M2M/IoT devices – In low-bandwidth applications.

  • Fallback for newer networks – When 3G/4G/5G is unavailable.

  • Rural and legacy systems – Where modern infrastructure is limited.

Which OSI layer does GSM belong to?

  • GSM spans multiple OSI layers, but its core signaling and control functions are implemented at Layer 2 and Layer 3. Here’s why: * Layer 2 (Data Link Layer): GSM uses LAPDm (Link Access Protocol on the Dm channel) for reliable communication between the mobile and BTS. * Layer 3 (Network Layer): GSM signaling protocols like RR (Radio Resource), MM (Mobility Management), and CM (Call Control) operate here to manage sessions, mobility,and call setup. * Layer 1 (Physical Layer): Handles radio transmission using TDMA and frequency hopping.

Is GSMI Windows specific?

No, GSMI (GSM Interface) is not Windows specific. It is a set of protocols and interfaces used in GSM cellular networks, independent of any desktop operating system.

Is GSMI Linux specific?

No, GSMI is not Linux specific. GSM interface protocols are implemented in network equipment and mobile devices, which may run on various operating systems including proprietary RTOS, Linux-based systems, or others.

Which Transport Protocol is used by GSMI?

GSMI protocols typically operate over signaling channels in the GSM network rather than traditional transport protocols like TCP or UDP. They use SS7 or MAP protocols over the signaling network.

Which Port is used by GSMI?

GSMI does not use standard TCP/UDP ports as it operates over GSM signaling links and dedicated channels in the mobile network infrastructure.

Is GSMI using Client server model?

No, GSMI interfaces do not follow a typical client-server model; they are part of a telecommunication signaling architecture involving network elements like BTS, BSC, MSC communicating via defined protocols.

Topics in this section,

  • In this section, you are going to learn

  • Terminology

  • Version Info

GSM Version

GSM Number

Year

Core Idea / Contribution

Phase 1

GSM 01.xx series

1991

Basic voice services, SMS, and circuit-switched data.

Phase 2

GSM 02.xx, 03.xx series

1995

Added supplementary services (call forwarding, barring), improved data rates.

Phase 2+

GSM 04.xx, 05.xx series

19971999

Introduced GPRS, EDGE, and enhanced SIM capabilities.

Release 99

TS 23.003, TS 24.008

1999

Unified GSM and UMTS core network architecture; foundation for 3G evolution.

Release 4

TS 23.002, TS 23.038

2001

Introduced MSC Server architecture and IP-based transport.

Release 5

TS 23.060, TS 23.040

2002

Added support for IMS and packet-switched voice (foundation for VoIP over GSM).

Release 6+

TS 23.272, TS 23.401

2004+

Continued enhancements for interworking with 3G/4G, improved data services, and security.

  • Setup

  • Setup

RR (Radio Resource) Setup Packet

S.No

Protocol Packets

Description

Size(Bytes)

1

RR (Radio Resource) Setup

Establishes a dedicated channel between MS and BTS.

~50100

Channel Request

Sent by MS to request a signaling channel.

~2030

Immediate Assignment

BTS assigns a channel to the MS.

~3050

MM (Mobility Management) Packet

S.No

Protocol Packets

Description

Size(Bytes)

2

MM (Mobility Management)

Handles location updates, authentication, and TMSI allocation.

~60120

Location Update Request

Sent by MS when entering a new location area.

~4060

Authentication Request/Response

Used to verify the identity of the subscriber.

~2040

CM (Call Control) Packet

S.No

Protocol Packets

Description

Size(Bytes)

3

CM (Call Control)

Manages call setup, modification, and release.

~80150

Setup

Initiates a call from the MS.

~4060

Call Confirm/Alerting

Indicates call progress to the MS.

~3050

Disconnect/Release

Terminates the call session.

~3040

SMS Packet(CP-DATA)

S.No

Protocol Packets

Description

Size(Bytes)

4

SMS Packet (CP-DATA)

Transports short messages between MS and SMSC.

~140176

SMS Submit/Deliver

Contains the actual message content.

~140 (max payload)

LAPDm Frame Packet

S.No

Protocol Packets

Description

Size(Bytes)

5

LAPDm Frame

Data link layer frame for reliable transmission over the air interface.

~23184

UI Frame

Unnumbered Information frame for signaling.

~2350

I Frame

Information frame for user data.

~50184

S.no

Use Case

Description

1

Voice Calls

Enables circuit-switched voice communication between mobile users.

2

SMS (Short Message Service)

Allows sending and receiving of short text messages (up to 160 characters).

3

Mobile Roaming

Supports international roaming by allowing users to access services abroad.

4

GPRS/EDGE Data Services

Provides packet-switched data for internet access and multimedia messaging.

5

Caller ID and Call Forwarding

Offers supplementary services like call waiting, barring, and redirection.

6

Emergency Calling (112/911)

Enables access to emergency services even without a SIM card.

7

SIM-Based Authentication

Uses SIM cards for secure user identification and network access.

8

M2M and IoT Connectivity

Used in low-bandwidth IoT applications like smart meters and vehicle tracking.

9

Mobile Banking & Payments

Supports USSD and SMS-based financial services in developing regions.

10

Fallback for Modern Networks

Acts as a backup when 3G/4G/5G coverage is unavailable.

S.no

Feature

Description

1

Digital Voice Transmission

Converts analog voice to digital signals for clearer and more efficient calls.

2

SIM-Based Authentication

Uses SIM cards to securely identify and authenticate users.

3

International Roaming

Allows users to access mobile services across different countries and networks.

4

SMS Support

Enables sending and receiving short text messages.

5

Call and Message Encryption

Provides basic encryption for voice and SMS to protect user privacy.

6

Supplementary Services

Includes call forwarding, call waiting, caller ID, and barring services.

7

Efficient Spectrum Usage

Uses TDMA and frequency reuse to maximize network capacity.

8

Low Power Consumption

Optimized for longer battery life in mobile devices.

9

Emergency Calling

Supports emergency calls even without a SIM card or network registration.

10

Support for Data Services

Offers GPRS and EDGE for basic internet and multimedia messaging.

Digital Voice Transmission - Testcases

#

Test Case

Description

Expected Result

1

Voice Input Sampling

Capture analog voice input

Signal is sampled correctly

2

A/D Conversion

Convert analog signal to digital

Digital signal is generated

3

Use of 13 kbps Codec

Encode voice using GSM Full Rate codec

Voice is compressed to 13 kbps

4

Use of Half Rate Codec

Encode voice using GSM Half Rate codec

Voice is compressed to 5.6 kbps

5

Use of Enhanced Full Rate Codec

Encode voice using EFR codec

Improved voice quality

6

Voice Frame Generation

Generate 20 ms voice frames

Frames are correctly formed

7

Frame Interleaving

Interleave voice frames

Frames are spread across time slots

8

Voice Frame Transmission

Transmit voice frames over air interface

Frames are sent without loss

9

Frame De-interleaving

Reconstruct original frame order

Voice is intelligible

10

D/A Conversion

Convert digital signal back to analog

Audio is played clearly

11

Voice Quality Test

Measure MOS (Mean Opinion Score)

Score is acceptable (>3.5)

12

Background Noise Suppression

Suppress ambient noise during call

Voice is clearer

13

Echo Cancellation

Remove echo from voice signal

Echo is not heard

14

Voice Activity Detection

Detect when user is speaking

Silence is not transmitted

15

Comfort Noise Generation

Generate background noise during silence

Natural call experience

16

Bit Error Resilience

Handle bit errors in transmission

Voice remains intelligible

17

Use of TCH/F Channel

Use full-rate traffic channel

Voice is transmitted

18

Use of TCH/H Channel

Use half-rate traffic channel

Voice is transmitted

19

Handover During Call

Maintain call during cell change

No voice dropouts

20

Voice Delay Measurement

Measure end-to-end delay

Delay < 150 ms

21

Voice Clarity in Urban Area

Test call in high-interference area

Voice remains clear

22

Voice Clarity in Rural Area

Test call in low-signal area

Voice is acceptable

23

Voice Clarity in Moving Vehicle

Test call while driving

Voice is stable

24

Voice Clarity in Elevator

Test call in enclosed metal space

Voice is intelligible

25

Voice Clarity in Tunnel

Test call in tunnel

Voice is maintained

26

Codec Negotiation

Switch between codecs based on network

Best codec is selected

27

Call Setup Time

Measure time to establish voice call

Setup < 5 seconds

28

Call Drop Rate

Measure frequency of dropped calls

Drop rate < 2%

29

Call Retainability

Maintain call for long duration

No unexpected drops

30

Call Accessibility

Ability to initiate call

Call connects successfully

31

Voice Encryption

Encrypt voice data

Data is secure

32

Voice Decryption

Decrypt voice data

Audio is intelligible

33

Voice Compression Efficiency

Measure compression ratio

Efficient compression

34

Voice Packet Loss Recovery

Handle lost voice packets

Minimal impact on quality

35

Voice Latency in Roaming

Measure delay during international call

Delay is acceptable

36

Voice Quality in 2G Network

Test voice on GSM-only network

Quality is acceptable

37

Voice Quality in 3G/4G Fallback

Test GSM fallback from higher networks

Voice remains stable

38

Voice Quality with Weak Signal

Test call at cell edge

Voice is still intelligible

39

Voice Quality with Interference

Introduce RF interference

Voice is resilient

40

Voice Quality with Multipath

Simulate multipath fading

Voice is clear

41

Voice Quality with Jitter

Introduce jitter in transmission

Voice is smooth

42

Voice Quality with Delay Spread

Simulate delay spread

Voice is understandable

43

Voice Quality with Codec Switching

Switch codecs mid-call

No noticeable degradation

44

Voice Quality with Congestion

Simulate network congestion

Voice is prioritized

45

Voice Quality with Power Saving Mode

Enable DTX (Discontinuous Transmission)

Battery is saved, voice is unaffected

46

Voice Quality with Handover

Perform intra-BSC handover

Voice is uninterrupted

47

Voice Quality with Inter-BSC Handover

Perform inter-BSC handover

Voice is uninterrupted

48

Voice Quality with Inter-MSC Handover

Perform inter-MSC handover

Voice is uninterrupted

49

Voice Quality with Codec Mismatch

Use different codecs at each end

Transcoding is successful

50

Voice Quality with Encryption Enabled

Enable A5/1 or A5/3 encryption

Voice is secure and clear

SIM-Based Authentication - Testcases

#

Test Case

Description

Expected Result

1

SIM Insertion Detection

Insert SIM into device

SIM is detected

2

SIM Removal Detection

Remove SIM from device

Device shows SIM removed

3

IMSI Retrieval

Read IMSI from SIM

IMSI is retrieved correctly

4

Authentication Request Generation

Network sends RAND challenge

SIM receives challenge

5

Authentication Response Generation

SIM computes SRES using Ki and RAND

SRES is generated correctly

6

Authentication Response Verification

Network compares received SRES

Match confirms authentication

7

Ki Confidentiality

Ensure Ki is not transmitted over air

Ki remains secure

8

TMSI Assignment

Assign temporary identity after authentication

TMSI is used instead of IMSI

9

SIM Lock Activation

Enable SIM PIN

Device prompts for PIN

10

SIM Lock Verification

Enter correct SIM PIN

Access granted

11

SIM Lock Failure

Enter incorrect SIM PIN

Access denied

12

SIM PUK Unlock

Unlock SIM with PUK after PIN failures

SIM is unlocked

13

SIM Authentication Retry Limit

Exceed PIN retry limit

SIM is blocked

14

SIM Authentication Timeout

Delay response from SIM

Authentication fails

15

SIM Authentication in Roaming

Authenticate on visited network

Authentication succeeds

16

SIM Authentication on 2G

Authenticate on GSM network

Authentication succeeds

17

SIM Authentication on 3G

Authenticate on UMTS network

Authentication succeeds

18

SIM Authentication on 4G

Authenticate on LTE network

Authentication succeeds

19

SIM Authentication on 5G

Authenticate on 5G NSA/SA network

Authentication succeeds

20

SIM Toolkit Access

Access SIM Toolkit menu

Menu is displayed

21

SIM File System Access

Read EF files from SIM

Files are accessible

22

SIM Profile Validation

Check SIM profile against network

Profile is valid

23

SIM Card Type Detection

Detect 2G/3G/4G/5G SIM

Type is correctly identified

24

SIM Card Size Compatibility

Use nano/micro/standard SIM

Device accepts SIM

25

SIM Swap Detection

Detect change in SIM

Network triggers re-authentication

26

SIM Cloning Attempt

Use cloned SIM

Authentication fails

27

SIM Authentication Logging

Log authentication events

Logs are accurate

28

SIM Authentication Encryption

Encrypt authentication messages

Messages are secure

29

SIM Authentication with A3 Algorithm

Use A3 algorithm for SRES

Response is valid

30

SIM Authentication with A8 Algorithm

Use A8 algorithm for Kc

Cipher key is generated

31

SIM Authentication with MILENAGE

Use MILENAGE algorithm (3G/4G)

Authentication succeeds

32

SIM Authentication with XOR

Use XOR algorithm (fallback)

Authentication succeeds

33

SIM Authentication Failure Handling

Handle failed authentication

Retry or deny access

34

SIM Authentication Retry Mechanism

Retry after failed attempt

Authentication succeeds

35

SIM Authentication in Dual SIM Device

Authenticate both SIMs

Both are authenticated independently

36

SIM Authentication in eSIM

Authenticate embedded SIM

Authentication succeeds

37

SIM Authentication in M2M Device

Authenticate SIM in IoT module

Authentication succeeds

38

SIM Authentication in VoLTE

Authenticate for voice over LTE

Authentication succeeds

39

SIM Authentication in VoWiFi

Authenticate for Wi-Fi calling

Authentication succeeds

40

SIM Authentication in IMS

Authenticate for IP Multimedia Subsystem

Authentication succeeds

41

SIM Authentication in Emergency Call

Attempt emergency call without SIM

Limited access granted

42

SIM Authentication in Airplane Mode

Attempt authentication in airplane mode

Authentication blocked

43

SIM Authentication in Weak Signal

Authenticate with low signal strength

Authentication may retry

44

SIM Authentication in High Load

Authenticate during network congestion

Authentication may delay

45

SIM Authentication in Handover

Maintain authentication during cell change

Session remains valid

46

SIM Authentication in Power Cycle

Re-authenticate after reboot

Authentication succeeds

47

SIM Authentication in Network Switch

Switch between 2G/3G/4G

Authentication re-established

48

SIM Authentication in IMSI Catcher

Attempt authentication with rogue base station

Authentication fails or alerts triggered

49

SIM Authentication with OTA Update

Authenticate after SIM OTA update

Authentication succeeds

50

SIM Authentication with Multi-IMSI

Authenticate using alternate IMSI

Authentication succeeds

International Roaming - Testcases

#

Test Case

Description

Expected Result

1

Roaming SIM Detection

Insert SIM in foreign country

Network is detected

2

Automatic Network Selection

Enable auto network selection

Device registers to preferred roaming partner

3

Manual Network Selection

Manually select available network

Device connects if allowed

4

IMSI Retrieval in Roaming

Retrieve IMSI from SIM

IMSI is read correctly

5

Authentication with Visited Network

Authenticate with foreign network

Authentication succeeds

6

Location Update in Roaming

Perform location update

Update is accepted

7

TMSI Assignment in Roaming

Assign temporary ID in visited network

TMSI is used

8

Call Setup in Roaming

Make outgoing call

Call connects successfully

9

Call Reception in Roaming

Receive incoming call

Call is received

10

SMS Sending in Roaming

Send SMS from visited network

SMS is delivered

11

SMS Receiving in Roaming

Receive SMS while roaming

SMS is received

12

Data Session in Roaming

Start mobile data session

Data is transmitted

13

APN Configuration in Roaming

Use correct APN for roaming

Data session is established

14

Roaming Profile Validation

Check if roaming is enabled on SIM

Profile allows roaming

15

Roaming Restrictions Enforcement

Try to roam with restricted SIM

Access is denied

16

Roaming Zone Detection

Detect roaming zone (e.g., EU, Global)

Zone is correctly identified

17

Roaming Tariff Notification

Receive tariff SMS on roaming

Notification is received

18

Roaming Call Quality

Measure voice quality during roaming call

Quality is acceptable

19

Roaming Data Speed

Measure data speed while roaming

Speed is within expected range

20

Roaming Handover

Move between roaming networks

Call/data session is maintained

21

Roaming with Dual SIM

Use roaming on one SIM

Roaming works independently

22

Roaming in Airplane Mode

Enable airplane mode and disable

Roaming resumes

23

Roaming in Border Area

Switch between home and foreign network

Seamless transition

24

Roaming in Weak Signal Area

Test roaming in low coverage

Network is retained

25

Roaming in High Load Area

Test roaming in congested network

Services remain accessible

26

Roaming with VoLTE

Use VoLTE while roaming

Voice over LTE works

27

Roaming with VoWiFi

Use Wi-Fi calling while roaming

Call connects via Wi-Fi

28

Roaming with IMS

Use IMS services while roaming

Services are accessible

29

Roaming with VPN

Use VPN over roaming data

VPN connects successfully

30

Roaming with eSIM

Use eSIM profile in foreign country

Roaming works

31

Roaming with 2G Network

Roam on legacy GSM network

Services are available

32

Roaming with 3G Network

Roam on UMTS network

Services are available

33

Roaming with 4G Network

Roam on LTE network

Services are available

34

Roaming with 5G Network

Roam on 5G NSA/SA network

Services are available

35

Roaming Billing Accuracy

Check billing for roaming usage

Charges match usage

36

Roaming Usage Limit Alert

Reach data usage threshold

Alert is triggered

37

Roaming Usage Blocking

Exceed data cap

Data is blocked or throttled

38

Roaming Call Forwarding

Enable call forwarding while roaming

Calls are forwarded correctly

39

Roaming Voicemail Access

Access voicemail from abroad

Voicemail is accessible

40

Roaming Emergency Call

Make emergency call while roaming

Call connects to local emergency services

41

Roaming SIM Toolkit

Access SIM Toolkit menu abroad

Menu is functional

42

Roaming OTA Update

Receive SIM OTA update while roaming

Update is applied

43

Roaming Network Blacklist

Attempt to connect to blacklisted network

Connection is denied

44

Roaming Network Whitelist

Connect to preferred roaming partner

Connection is allowed

45

Roaming with Multi-IMSI SIM

Use alternate IMSI for roaming

Authentication succeeds

46

Roaming with IMSI Catcher Detection

Detect rogue base station abroad

Alert is triggered

47

Roaming with SIM Swap Detection

Detect SIM change while roaming

Security alert is triggered

48

Roaming with Secure Authentication

Use AKA/MILENAGE authentication

Authentication succeeds

49

Roaming with Encryption

Encrypt voice/data during roaming

Communication is secure

50

Roaming Session Logging

Log all roaming activity

Logs are complete and accurate

SMS Support - Testcases

#

Test Case

Description

Expected Result

1

Send SMS to Valid Number

Send SMS to a reachable mobile number

SMS is delivered successfully

2

Receive SMS from Valid Number

Receive SMS from another mobile

SMS is received

3

Send SMS to Invalid Number

Send SMS to a non-existent number

Error or failure report

4

Receive SMS from Unknown Number

Receive SMS from unlisted contact

SMS is displayed

5

Send Long SMS

Send message >160 characters

Message is split and reassembled

6

Receive Long SMS

Receive multipart SMS

Message is reassembled correctly

7

Send SMS with Special Characters

Include emojis or symbols

Characters are displayed correctly

8

Send SMS with Unicode

Send message in non-Latin script (e.g., Hindi, Arabic)

Message is received correctly

9

Send Flash SMS

Send Class 0 SMS

Message appears instantly on screen

10

Send SMS with Delivery Report

Request delivery confirmation

Delivery report is received

11

Send SMS in Roaming

Send SMS while abroad

SMS is delivered

12

Receive SMS in Roaming

Receive SMS while abroad

SMS is received

13

Send SMS in Weak Signal Area

Send SMS with low signal

SMS is queued or delayed

14

Receive SMS in Weak Signal Area

Receive SMS with poor coverage

SMS is delayed or queued

15

Send SMS in Airplane Mode

Attempt to send SMS while offline

SMS fails to send

16

Receive SMS in Airplane Mode

Turn off airplane mode

Queued SMS is received

17

Send SMS to Landline

Send SMS to a fixed-line number

SMS fails or is converted to voice

18

Send SMS to Email Gateway

Send SMS to email address via gateway

Email is received

19

Send SMS to Short Code

Send SMS to service number (e.g., 12345)

Service responds

20

Receive SMS from Short Code

Receive promotional or service SMS

SMS is displayed

21

Send SMS with SIM 1

Send SMS using SIM 1 in dual SIM device

SMS is sent via SIM 1

22

Send SMS with SIM 2

Send SMS using SIM 2

SMS is sent via SIM 2

23

SMS Center Configuration

Set correct SMSC number

SMS is routed correctly

24

SMS Center Misconfiguration

Use incorrect SMSC

SMS fails to send

25

SMS Storage on SIM

Store SMS on SIM card

Message is saved

26

SMS Storage on Phone

Store SMS in phone memory

Message is saved

27

SMS Inbox Full

Fill SMS storage

New messages are rejected or overwrite

28

SMS Deletion

Delete SMS from inbox

Message is removed

29

SMS Backup

Export SMS to cloud or file

Messages are backed up

30

SMS Restore

Import SMS from backup

Messages are restored

31

SMS Notification

Receive SMS while screen is off

Notification is shown

32

Silent SMS

Receive silent SMS (no alert)

Message is logged silently

33

SMS Blocking

Block SMS from specific number

Message is not shown

34

SMS Spam Detection

Detect spam message

Message is flagged

35

SMS Encryption

Encrypt SMS content

Message is secure

36

SMS Decryption

Decrypt received SMS

Message is readable

37

SMS Timestamp Accuracy

Check timestamp of received SMS

Time is accurate

38

SMS Retry Mechanism

Retry sending failed SMS

SMS is sent on retry

39

SMS Queue Management

Queue multiple SMS for sending

Messages are sent in order

40

SMS with Attachment (MMS Fallback)

Attempt to send media via SMS

Converted to MMS or fails

41

SMS via USSD

Send SMS through USSD menu

Message is sent

42

SMS via SIM Toolkit

Send SMS using SIM app

Message is sent

43

SMS via Web Interface

Send SMS from web portal

Message is delivered

44

SMS via API

Send SMS using SMS gateway API

Message is delivered

45

SMS in Emergency Mode

Send SMS during emergency call mode

Message is prioritized

46

SMS in Do Not Disturb Mode

Receive SMS while DND is active

Message is received silently

47

SMS in Power Saving Mode

Send/receive SMS with battery saver on

SMS works normally

48

SMS in Group Chat App (Fallback)

Use SMS fallback in messaging app

Message is sent via SMS

49

SMS in Feature Phone

Send/receive SMS on basic phone

SMS works correctly

50

SMS in Smartwatch

Send/receive SMS on wearable device

SMS is displayed and sent

Call and Message Encryption - Testcases

#

Test Case

Description

Expected Result

1

Enable Call Encryption

Initiate encrypted voice call

Call is encrypted

2

Enable SMS Encryption

Send encrypted SMS

Message is encrypted

3

Use A5/1 Algorithm

Encrypt call using A5/1

Encryption is applied

4

Use A5/2 Algorithm

Encrypt call using A5/2

Encryption is applied (less secure)

5

Use A5/3 Algorithm

Encrypt call using A5/3

Strong encryption is applied

6

Use A5/0 (No Encryption)

Disable encryption intentionally

Call is unencrypted

7

Encryption Status Display

Show encryption icon during call

Icon is visible

8

Encryption Key Generation

Generate session key for call

Key is securely generated

9

Encryption Key Exchange

Exchange keys between MS and BTS

Keys are exchanged securely

10

Ciphering Command from Network

Receive ciphering command

Device starts encryption

11

Ciphering Mode Complete

Confirm encryption activation

Network acknowledges

12

Encryption Activation Timing

Measure time to activate encryption

Activation is fast (<1s)

13

Encryption in Roaming

Use encryption while roaming

Encryption is maintained

14

Encryption in Weak Signal

Maintain encryption with low signal

Encryption persists

15

Encryption in Handover

Maintain encryption during cell switch

No interruption in encryption

16

Encryption in Emergency Call

Make emergency call

Encryption may be disabled (per spec)

17

Encryption in SMS Delivery

Encrypt SMS content

Message is secure

18

Encryption in SMS Storage

Store encrypted SMS on SIM/phone

Message remains encrypted

19

Encryption in SMS Forwarding

Forward encrypted SMS

Message remains secure

20

Encryption in Group SMS

Send encrypted group message

All recipients receive encrypted content

21

Encryption in Flash SMS

Send encrypted Class 0 SMS

Message is secure

22

Encryption in SIM Toolkit SMS

Send encrypted SMS via SIM app

Message is encrypted

23

Encryption in OTA Update

Receive encrypted SIM update

Update is secure

24

Encryption in VoLTE

Encrypt voice over LTE

Call is secure

25

Encryption in VoWiFi

Encrypt voice over Wi-Fi

Call is secure

26

Encryption in IMS

Use encryption in IP Multimedia Subsystem

Media and signaling are encrypted

27

Encryption in 2G Network

Use A5/1 or A5/3 in GSM

Call is encrypted

28

Encryption in 3G Network

Use KASUMI cipher

Call is encrypted

29

Encryption in 4G Network

Use SNOW 3G or AES

Call is encrypted

30

Encryption in 5G Network

Use 128-NEA and 128-NIA

Call and data are encrypted

31

Encryption Key Refresh

Refresh encryption keys mid-call

Session remains secure

32

Encryption Key Expiry

Handle expired encryption key

New key is generated

33

Encryption Failure Handling

Simulate encryption failure

Call is dropped or downgraded

34

Encryption Downgrade Attack Detection

Detect forced downgrade to A5/0

Alert is triggered

35

Encryption Logging

Log encryption status

Logs show ciphering activity

36

Encryption Policy Enforcement

Enforce encryption-only policy

Unencrypted calls are blocked

37

Encryption with Dual SIM

Use encryption on both SIMs

Encryption works independently

38

Encryption with eSIM

Use encryption with embedded SIM

Encryption is active

39

Encryption with SIM Swap

Detect SIM change during encrypted session

Session is terminated

40

Encryption with IMSI Catcher

Detect rogue BTS disabling encryption

Alert is triggered

41

Encryption with Silent SMS

Send encrypted silent SMS

Message is secure

42

Encryption with OTA Key Provisioning

Receive encryption keys over the air

Keys are securely installed

43

Encryption with Secure Boot

Ensure encryption keys are protected at boot

Keys are intact

44

Encryption with Secure Element

Store keys in secure hardware

Keys are protected

45

Encryption with SIM Applet

Use SIM applet for encryption

Message is encrypted

46

Encryption with Smartwatch

Use encryption in wearable device

Call/SMS is secure

47

Encryption with Feature Phone

Use basic encryption on 2G phone

Call is encrypted

48

Encryption with Smartphone App

Use app-based encryption (e.g., Signal fallback)

Message is encrypted

49

Encryption with Cloud Backup

Backup encrypted SMS

Data remains encrypted

50

Encryption Compliance Check

Verify compliance with GSM encryption standards

Device passes test

Supplementary Services - Testcases

#

Test Case

Description

Expected Result

1

Activate Call Forwarding (Unconditional)

Forward all calls to another number

Calls are forwarded automatically

2

Activate Call Forwarding (Busy)

Forward calls when line is busy

Calls are forwarded when busy

3

Activate Call Forwarding (No Reply)

Forward calls after timeout

Calls are forwarded after delay

4

Activate Call Forwarding (Unreachable)

Forward calls when phone is off

Calls are forwarded

5

Deactivate Call Forwarding

Turn off all call forwarding options

Calls ring normally

6

Check Call Forwarding Status

Query current forwarding settings

Status is displayed

7

Activate Call Waiting

Enable notification for incoming call during active call

Notification is received

8

Deactivate Call Waiting

Disable call waiting

Second call is rejected

9

Call Waiting Notification

Receive second call while on call

Notification is shown

10

Switch Between Calls

Toggle between two active calls

Active call is switched

11

Merge Calls (Conference)

Merge two calls into a conference

All parties are connected

12

Caller ID Display

Show callers number on incoming call

Number is displayed

13

Caller ID Restriction

Hide callers number

Number is hidden

14

Caller ID Request

Request caller ID from network

Number is shown if available

15

Activate Call Barring (All Outgoing)

Block all outgoing calls

Outgoing calls are blocked

16

Activate Call Barring (International)

Block international calls

International calls are blocked

17

Activate Call Barring (Incoming)

Block all incoming calls

Incoming calls are blocked

18

Deactivate Call Barring

Remove all call barring

Calls are allowed

19

Call Barring Password Change

Change barring password

Password is updated

20

Call Barring Status Check

Query current barring settings

Status is displayed

21

Call Forwarding to Voicemail

Forward calls to voicemail

Voicemail answers

22

Call Waiting with Voicemail

Receive second call while first goes to voicemail

First call is recorded

23

Call Forwarding Loop Prevention

Prevent forwarding loops

Loop is blocked

24

Call Waiting with Conference

Add waiting call to conference

All calls are merged

25

Call Forwarding to International Number

Forward to number abroad

Call is forwarded

26

Call Forwarding with DND

Forward calls while Do Not Disturb is active

Calls are forwarded

27

Call Waiting in Roaming

Use call waiting while roaming

Feature works

28

Call Forwarding in Roaming

Forward calls while roaming

Calls are forwarded

29

Call Barring in Roaming

Apply barring while roaming

Calls are blocked

30

Call Waiting with Data Session

Receive call during data usage

Notification is shown

31

Call Forwarding with Dual SIM

Forward calls from SIM 1

Calls are forwarded correctly

32

Call Waiting with Dual SIM

Receive second call on SIM 2

Notification is received

33

Call Barring with Dual SIM

Block calls on one SIM

Calls are blocked on selected SIM

34

Call Forwarding Activation via USSD

Use USSD code to activate forwarding

Forwarding is enabled

35

Call Waiting Activation via USSD

Use USSD code to activate call waiting

Feature is enabled

36

Call Barring Activation via USSD

Use USSD code to activate barring

Feature is enabled

37

Call Forwarding Notification

Notify user when call is forwarded

Notification is shown

38

Call Waiting Notification Tone

Hear tone during active call

Tone is audible

39

Call Barring with Emergency Call

Attempt emergency call with barring active

Emergency call is allowed

40

Call Forwarding with SIM Toolkit

Activate via SIM menu

Forwarding is enabled

41

Call Waiting with VoLTE

Use call waiting on VoLTE call

Feature works

42

Call Forwarding with VoWiFi

Forward calls while on Wi-Fi calling

Calls are forwarded

43

Call Barring with VoLTE

Block outgoing VoLTE calls

Calls are blocked

44

Call Waiting with IMS

Use call waiting in IMS

Feature works

45

Call Forwarding with IMS

Forward IMS-based calls

Calls are forwarded

46

Call Barring with IMS

Block IMS-based calls

Calls are blocked

47

Call Waiting with Video Call

Receive second call during video call

Notification is shown

48

Call Forwarding to SIP Number

Forward to VoIP/SIP number

Call is forwarded

49

Call Barring Password Retry Limit

Enter wrong password repeatedly

Barring is locked

50

Call Forwarding with Expiry Timer

Set forwarding for limited time

Forwarding expires as scheduled

Efficient Spectrum Usage - Testcases

#

Test Case

Description

Expected Result

1

TDMA Slot Allocation

Assign time slots to users

Slots are allocated without conflict

2

TDMA Frame Synchronization

Synchronize mobile with base station

Timing is aligned

3

TDMA Slot Timing Accuracy

Measure slot timing jitter

Within acceptable limits

4

TDMA Slot Handover

Maintain slot during cell handover

No call drop

5

Frequency Reuse Pattern

Apply reuse pattern (e.g., 3/9)

Interference is minimized

6

Co-channel Interference Test

Measure interference from reused frequencies

Signal quality is acceptable

7

Adjacent Channel Interference Test

Measure interference from neighboring channels

Interference is within limits

8

Frequency Planning Validation

Validate frequency reuse plan

Plan meets capacity and coverage goals

9

Dynamic Frequency Allocation

Allocate frequencies based on load

Spectrum is used efficiently

10

Frequency Hopping Activation

Enable frequency hopping

Hopping is active

11

Frequency Hopping Performance

Measure call quality with hopping

Quality improves or remains stable

12

TDMA with Voice Call

Make a voice call using TDMA slot

Call is clear

13

TDMA with SMS

Send SMS using control channel

Message is delivered

14

TDMA with Data Session

Use GPRS/EDGE over TDMA

Data is transmitted

15

TDMA Slot Reuse in Neighboring Cell

Use same slot in adjacent cell

No interference

16

Cell Sectorization Efficiency

Use 3-sector antennas

Capacity increases

17

Frequency Reuse in Urban Area

Deploy reuse pattern in dense area

Network handles high load

18

Frequency Reuse in Rural Area

Use wider reuse pattern

Coverage is maximized

19

TDMA Slot Collision Detection

Detect overlapping transmissions

Collisions are avoided

20

TDMA Slot Guard Period

Verify guard time between slots

No overlap occurs

21

TDMA Slot Power Control

Adjust power per slot

Interference is reduced

22

TDMA Slot Allocation in Handover

Allocate new slot during handover

Seamless transition

23

Frequency Reuse with Indoor Coverage

Use microcells with reuse

Indoor coverage is effective

24

Frequency Reuse with Outdoor Coverage

Use macrocells with reuse

Outdoor coverage is effective

25

TDMA Slot Allocation in Congestion

Allocate slots under high load

Calls are managed efficiently

26

TDMA Slot Allocation in Idle Network

Allocate slots with low traffic

Resources are conserved

27

Frequency Reuse with Repeaters

Use repeaters in reused frequencies

No interference introduced

28

Frequency Reuse with Pico Cells

Use small cells in reuse plan

Capacity is increased

29

TDMA Slot Allocation for Emergency

Prioritize emergency calls

Slot is allocated immediately

30

Frequency Reuse with Load Balancing

Shift load between cells

Spectrum is balanced

31

TDMA Slot Allocation for Data

Allocate slots for GPRS/EDGE

Data is transmitted

32

TDMA Slot Allocation for Voice

Allocate slots for voice

Call is established

33

Frequency Reuse with Interference Avoidance

Avoid reuse in high-interference zones

Signal quality is maintained

34

TDMA Slot Allocation in Dual Band

Use 900/1800 MHz bands

Slots are allocated correctly

35

Frequency Reuse in Multi-Operator Area

Share spectrum with other operators

No cross-interference

36

TDMA Slot Allocation in Roaming

Allocate slots for roaming user

Call is connected

37

Frequency Reuse with Smart Antennas

Use beamforming to reduce interference

Capacity is improved

38

TDMA Slot Allocation with QoS

Prioritize high-QoS users

Slots are allocated accordingly

39

Frequency Reuse with Inter-BTS Sync

Synchronize base stations

Interference is minimized

40

TDMA Slot Allocation with Paging

Allocate slot for paging

User is notified

41

Frequency Reuse with Guard Bands

Use guard bands between channels

Crosstalk is reduced

42

TDMA Slot Allocation with Broadcast

Use slot for system broadcast

Message is received

43

Frequency Reuse with Frequency Planning Tool

Simulate reuse plan

Plan is optimized

44

TDMA Slot Allocation with Encryption

Encrypt data in slot

Data is secure

45

Frequency Reuse with Interference Monitoring

Monitor spectrum usage

Interference is detected and managed

46

TDMA Slot Allocation with Power Saving

Use DTX to save power

Battery life is extended

47

Frequency Reuse with Spectrum Analyzer

Measure spectrum efficiency

Usage is optimized

48

TDMA Slot Allocation with Load Forecasting

Predict and allocate slots

Network is prepared

49

Frequency Reuse with AI Optimization

Use AI to optimize reuse

Capacity is maximized

50

TDMA Slot Allocation with Multi-SIM

Allocate slots for dual SIM device

Both SIMs operate efficiently

Low Power Consumption - Testcases

#

Test Case

Description

Expected Result

1

Enable Discontinuous Transmission (DTX)

Activate DTX during silence periods

Power usage is reduced

2

Enable Discontinuous Reception (DRX)

Activate DRX in idle mode

Battery life is extended

3

Measure Power in Idle Mode

Monitor power usage when idle

Consumption is minimal

4

Measure Power in Standby Mode

Monitor power usage in standby

Consumption is low

5

Measure Power During Voice Call

Monitor battery usage during call

Within expected limits

6

Measure Power During SMS

Monitor battery usage while sending SMS

Minimal power used

7

Measure Power During Data Session

Monitor battery usage during GPRS/EDGE session

Usage is efficient

8

Power Consumption with DTX Off

Disable DTX and measure power

Consumption increases

9

Power Consumption with DRX Off

Disable DRX and measure power

Consumption increases

10

Power Saving in Weak Signal Area

Test power usage with poor signal

Device increases power use moderately

11

Power Saving in Strong Signal Area

Test power usage with strong signal

Device uses minimal power

12

Battery Life in Idle State

Measure standby time

Battery lasts several days

13

Battery Life in Active State

Measure talk time

Battery lasts as per spec

14

Power Usage During Handover

Measure power during cell switch

No significant spike

15

Power Usage During Roaming

Measure power while roaming

Usage remains efficient

16

Power Usage with Background Apps

Run background apps

GSM usage remains low

17

Power Usage with Dual SIM

Use two SIMs simultaneously

Battery usage is optimized

18

Power Usage with SIM Toolkit

Use SIM Toolkit app

Minimal impact on battery

19

Power Usage with Call Forwarding

Enable call forwarding

No extra power used

20

Power Usage with Call Waiting

Enable call waiting

No extra power used

21

Power Usage with Encryption Enabled

Enable A5/1 or A5/3 encryption

Slight increase, within limits

22

Power Usage with SMS Encryption

Send encrypted SMS

Minimal impact

23

Power Usage During Paging

Monitor power during paging cycles

DRX optimizes usage

24

Power Usage During Cell Reselection

Measure power during idle reselection

Usage is efficient

25

Power Usage During Location Update

Measure power during periodic updates

Usage is optimized

26

Power Usage with Frequency Hopping

Enable hopping

No significant increase

27

Power Usage with Static Frequency

Disable hopping

Usage remains stable

28

Power Usage with TDMA Slot Allocation

Use assigned time slot

Power is conserved

29

Power Usage with GPRS Idle

Stay connected to GPRS without data

DRX reduces power

30

Power Usage with GPRS Active

Transmit data via GPRS

Usage is efficient

31

Power Usage with EDGE Active

Transmit data via EDGE

Usage is efficient

32

Power Usage with Cell Broadcast

Receive broadcast messages

Minimal power used

33

Power Usage with Emergency Call

Make emergency call

Usage is normal

34

Power Usage with SIM Swap

Swap SIM cards

No abnormal power usage

35

Power Usage with OTA Update

Receive SIM OTA update

Usage is optimized

36

Power Usage with Network Search

Search for network manually

Temporary increase, returns to idle

37

Power Usage with Auto Network Select

Use automatic selection

Efficient scanning

38

Power Usage with Airplane Mode

Enable airplane mode

Power usage drops significantly

39

Power Usage with Power Saving Mode

Enable device power saver

GSM usage is minimized

40

Power Usage with Background Sync Off

Disable background sync

GSM usage is reduced

41

Power Usage with VoLTE Off

Use GSM-only voice

Usage is optimized

42

Power Usage with VoWiFi Off

Use GSM-only voice

Usage is optimized

43

Power Usage with IMS Off

Use GSM fallback

Usage is optimized

44

Power Usage with SIM Applet Idle

Keep SIM applet running

Minimal impact

45

Power Usage with SIM Applet Active

Run SIM applet task

Slight increase, within limits

46

Power Usage with Cell Lock

Lock to specific cell

Reduces reselection power

47

Power Usage with Network Lock

Lock to specific network

Reduces scanning power

48

Power Usage with Low Battery

Operate under low battery condition

GSM functions remain stable

49

Power Usage with Battery Saver App

Use third-party saver app

GSM usage is optimized

50

Power Usage with Smartwatch Pairing

Pair with GSM-enabled wearable

Usage remains within expected limits

Emergency Calling - Testcases

#

Test Case

Description

Expected Result

1

Emergency Call with SIM

Make emergency call with active SIM

Call connects to emergency services

2

Emergency Call without SIM

Remove SIM and dial emergency number

Call connects successfully

3

Emergency Call with Locked SIM

Use SIM with PIN lock

Emergency call is allowed

4

Emergency Call with No Network

No network coverage

Call attempts on any available network

5

Emergency Call with Roaming Disabled

Roaming turned off

Emergency call still connects

6

Emergency Call in Airplane Mode

Enable airplane mode and dial emergency

Prompt to disable airplane mode

7

Emergency Call with No Credit

Prepaid balance is zero

Emergency call is allowed

8

Emergency Call with Barred SIM

Outgoing calls barred

Emergency call bypasses restriction

9

Emergency Call with Network Congestion

Simulate high traffic

Emergency call is prioritized

10

Emergency Call with 112

Dial 112

Call connects to emergency services

11

Emergency Call with 911

Dial 911

Call connects to emergency services

12

Emergency Call with 100

Dial 100 (India)

Call connects to police

13

Emergency Call with 101

Dial 101 (fire)

Call connects to fire department

14

Emergency Call with 102

Dial 102 (ambulance)

Call connects to ambulance

15

Emergency Call with 999

Dial 999 (UK)

Call connects to emergency services

16

Emergency Call with 000

Dial 000 (Australia)

Call connects to emergency services

17

Emergency Call with 08 Prefix

Dial emergency number with prefix

Call is routed correctly

18

Emergency Call with VoLTE

Use VoLTE for emergency call

Call connects successfully

19

Emergency Call with VoWiFi

Use Wi-Fi calling

Call connects if supported

20

Emergency Call with IMS

Use IMS-based emergency call

Call is routed correctly

21

Emergency Call with eSIM

Use eSIM profile

Emergency call is allowed

22

Emergency Call with Dual SIM

Use device with two SIMs

Call works regardless of SIM status

23

Emergency Call with Feature Phone

Use basic GSM phone

Emergency call connects

24

Emergency Call with Smartphone

Use smartphone

Emergency call connects

25

Emergency Call with Smartwatch

Use GSM-enabled wearable

Call connects to emergency services

26

Emergency Call with Locked Phone

Make call from lock screen

Emergency dialer is accessible

27

Emergency Call with No Battery

Attempt call with low battery

Call proceeds if battery allows

28

Emergency Call with SIM Toolkit

Access emergency via SIM menu

Call is initiated

29

Emergency Call with USSD Blocked

USSD disabled

Emergency call still works

30

Emergency Call with Network Lock

Device locked to specific network

Emergency call bypasses lock

31

Emergency Call with IMSI Catcher

Attempt call via rogue BTS

Call is blocked or redirected

32

Emergency Call with Encryption

Use encrypted call path

Call is secure

33

Emergency Call with Location Sharing

Share location during call

Location is transmitted

34

Emergency Call with GPS Off

GPS disabled

Network-based location is used

35

Emergency Call with GPS On

GPS enabled

Accurate location is shared

36

Emergency Call with Call Recording

Record emergency call

Recording is stored (if allowed)

37

Emergency Call with Call Timer

Measure call duration

Timer functions correctly

38

Emergency Call with Call Log Entry

Check call log after emergency call

Entry is recorded

39

Emergency Call with No Call Log

Privacy mode enabled

Call is not logged

40

Emergency Call with Language Prompt

Prompt for language selection

User selects preferred language

41

Emergency Call with Accessibility Mode

Use accessibility features

Emergency call is accessible

42

Emergency Call with Hearing Aid Mode

Use hearing aid compatibility

Call is audible

43

Emergency Call with Visual Alert

Flash or vibration on call connect

Alert is triggered

44

Emergency Call with Auto Redial

Retry if call fails

Call is retried automatically

45

Emergency Call with SIM Swap

Swap SIM during emergency call

Call continues or reconnects

46

Emergency Call with OTA Update

During SIM update

Emergency call is still allowed

47

Emergency Call with Network Switch

Switch between 2G/3G/4G

Call is maintained

48

Emergency Call with Power Saving Mode

Enable battery saver

Call is prioritized

49

Emergency Call with Do Not Disturb

DND enabled

Emergency call bypasses DND

50

Emergency Call with Airplane Crash Mode

Simulate crash detection

Emergency call is auto-initiated

Support for Data Services - Testcases

#

Test Case

Description

Expected Result

1

GPRS Activation

Enable GPRS on device

GPRS icon appears

2

EDGE Activation

Enable EDGE on device

EDGE icon appears

3

GPRS Network Registration

Register to GPRS network

PDP context is activated

4

EDGE Network Registration

Register to EDGE network

PDP context is activated

5

GPRS Data Session Start

Initiate data session

Data is transmitted

6

EDGE Data Session Start

Initiate EDGE session

Data is transmitted

7

GPRS IP Address Allocation

Obtain IP address

IP is assigned

8

EDGE IP Address Allocation

Obtain IP address

IP is assigned

9

GPRS DNS Resolution

Resolve domain name

DNS query succeeds

10

EDGE DNS Resolution

Resolve domain name

DNS query succeeds

11

GPRS Web Browsing

Open website using GPRS

Page loads successfully

12

EDGE Web Browsing

Open website using EDGE

Page loads successfully

13

GPRS Email Access

Access email via GPRS

Email syncs successfully

14

EDGE Email Access

Access email via EDGE

Email syncs successfully

15

GPRS MMS Sending

Send MMS over GPRS

MMS is delivered

16

EDGE MMS Sending

Send MMS over EDGE

MMS is delivered

17

GPRS MMS Receiving

Receive MMS over GPRS

MMS is received

18

EDGE MMS Receiving

Receive MMS over EDGE

MMS is received

19

GPRS Speed Test

Measure download/upload speed

Speed is within GPRS range (~56-114 kbps)

20

EDGE Speed Test

Measure download/upload speed

Speed is within EDGE range (~384 kbps)

21

GPRS Session Stability

Maintain long data session

No disconnection

22

EDGE Session Stability

Maintain long data session

No disconnection

23

GPRS Handover

Move between cells during session

Session is maintained

24

EDGE Handover

Move between cells during session

Session is maintained

25

GPRS Roaming

Use GPRS while roaming

Data session is established

26

EDGE Roaming

Use EDGE while roaming

Data session is established

27

GPRS with Dual SIM

Use GPRS on SIM 1

Data is transmitted

28

EDGE with Dual SIM

Use EDGE on SIM 2

Data is transmitted

29

GPRS with SIM Toolkit

Access SIM-based data service

Service is accessed

30

EDGE with SIM Toolkit

Access SIM-based data service

Service is accessed

31

GPRS with Static IP

Assign static IP

IP is assigned correctly

32

EDGE with Static IP

Assign static IP

IP is assigned correctly

33

GPRS with Dynamic IP

Use DHCP

IP is assigned dynamically

34

EDGE with Dynamic IP

Use DHCP

IP is assigned dynamically

35

GPRS with VPN

Connect to VPN over GPRS

Tunnel is established

36

EDGE with VPN

Connect to VPN over EDGE

Tunnel is established

37

GPRS with Proxy

Use HTTP proxy

Traffic is routed correctly

38

EDGE with Proxy

Use HTTP proxy

Traffic is routed correctly

39

GPRS with Firewall

Access internet with firewall

Access is controlled

40

EDGE with Firewall

Access internet with firewall

Access is controlled

41

GPRS with NAT

Use NAT for IP translation

Data flows correctly

42

EDGE with NAT

Use NAT for IP translation

Data flows correctly

43

GPRS Session Timeout

Leave session idle

Session is terminated after timeout

44

EDGE Session Timeout

Leave session idle

Session is terminated after timeout

45

GPRS Billing Accuracy

Track data usage

Usage matches billing

46

EDGE Billing Accuracy

Track data usage

Usage matches billing

47

GPRS with Power Saving Mode

Enable power saver

Data session remains stable

48

EDGE with Power Saving Mode

Enable power saver

Data session remains stable

49

GPRS with Background Sync

Sync apps in background

Data is synced

50

EDGE with Background Sync

Sync apps in background

Data is synced

  • Reference links