GSM MESSAGE FLOWS

CALL FLOW NO DESCRIPTION OF CALL FLOW

MESSAGE FLOW 1 MS Registration Procedure

MESSAGE FLOW 2 MS Originating Call

MESSAGE FLOW 3 MS Terminating Call

MESSAGE FLOW 4 SMS Originating

MESSAGE FLOW 5 SMS Terminating

MESSAGE FLOW 6 Intra-MSC Handover

MESSAGE FLOW 7 Inter-MSC Handover

MESSAGE FLOW 8 Inter-RAT Handover

Immediate Assignment

(Channel Description, Mobile

Allocation)

MM: Service Request (SDCCH)

(CM Service Type, MS Classmark,

MS Identity)

RR: Unnumbered

Acknowledgement

SCCP: Connection Request MM: Service Request

Immediate Assignment Command

() Immediate Assignment Command

(AGCH)

()

MM: Authentication Response

(SRES)

Authentication Response

(RAND) Authentication Request

RR: Channel Request (RACH)

(Establishment Cause)

(TCH, SAPI)

(CM Service Type, MS Classmark, MS

Identity)

Channel Request

(Establishment Cause)

Channel Activation

(Asks BTS to activate SDCCH or TCH)

Channel Activation Acknowledgment

Channel Request

(Establishment Cause)

Channel Activation

(Asks BSC to activate SDCCH or TCH)

Channel Activation Acknowledgment

RR: Unnumbered Acknowledgement

(TCH, SAPI)

RR: Location Update Request

Location Update Request

Location Update Request

Authentication Request

Authentication Request (RAND)

(RAND)

Authentication Response

(SRES)

Cipher Mode Command

(SRES)

(mode = CLEAR)

(IMSI)

MESSAGE FLOW 1:

MS Registration Process:

MS BTS BSC MSC/VLR

Cipher Mode Command

Location Update Accept

(TMSI)

Location Update Accept

(TMSI)

Location Update Accept

(TMSI)

Clear Command

Channel Release complete

(mode = CLEAR)

Channel Release

RR: Cipher Mode Command

Cipher Mode Complete

(mode = CIPHERED)

Clear Complete

(mode = CLEAR)

RR: Cipher Mode Complete

(mode = CIPHERED)

(mode = CIPHERED) Cipher Mode Complete

Clear Command

Clear Complete

MS BTS BSC MSC/VLR

RR: Assignment Command

(AGCH)

(Channel Description, Mobile

Allocation)

MM: Service Request (SDCCH)

(CM Service Type, MS Classmark,

MS Identity)

RR: Unnumbered

Acknowledgement

SCCP: Connection Request MM: Service Request

MM: Authentication Request

(RAND)

MM: Authentication Request

(RAND)

MM: Authentication Response

(SRES)

MM: Authentication Response

(SRES)

MM: Service Accept

BSSMAP: Cipher Mode Command

(mode = CLEAR)

BSSMAP: Cipher Mode Complete

CC: Call Setup

(MSISDN Number of Called Party)

CC: Call Proceeding

CC: Call Proceeding

RR: Channel Request (RACH)

(Establishment Cause)

(TCH, SAPI)

(CM Service Type, MS Classmark, MS

Identity)

MM: Service Accept

RR: Cipher Mode Command

RR: Cipher Mode Complete

(mode = CIPHERED)

CC: Call Setup

(MSISDN Number of Called Party)

(Bearer Capabilities)

(Indicates the call setup is being

attempted)

MESSAGE FLOW 2:

Mobile Originating Call:

MS BSS MSC/VLR PSTN

RR: Channel Mode Modify

BSSMAP: Assignment Request

ISUP: Initial Address Message

(SS7, Dialed Digits)

ISUP: Address Complete Message

(SS7)

CC: Call Alerting

(Ringing tone on handset)

ISUP: Answer

(SS7) CC: Connect

(Indicates UE that the end user has answered the call)

CC: Connect Acknowledgment

CC: Disconnect

(Either of the Users disconnects the call)

BSSMAP: Clear Command

ISUP: Release

CC: Release

CC: Release Complete

ISUP: Released

ISUP: Release Complete

RR: Channel Release

BSSMAP: Clear Complete

(Voice Circuit)

RR: Channel Mode Modify

Acknowledgment

BSSMAP: Assignment Complete

CC: Call Alerting

(Ringing tone on handset)

(SS7)

(SS7)

(SS7)

MS BSS MSC/VLR PSTN

Active Conversation between Calling and Called Party

RR: Channel Request (RACH)

SCCP: Connection Request

()

(RAND)

MM: Authentication Request

RR: Authentication Request

(RAND)

RR: Authentication Response

(SRES)

MM: Authentication Response

(SRES)

(mode = CIPHERED)

MM: Cipher Mode Command

RR: Cipher Mode Complete

MM: Cipher Mode Complete

CC: Call Setup

(Parameters required for Voice Calls, Called Party Mobile Number)

ISUP: Initial Address Message

(Paging Cause, TMSI)

BSSMAP: Paging

(Channel Description, Mobile

Allocation)

RR: Paging Response (SDCCH)

(TMSI, LAI, Classmark)

RR: Immediate Assignment

(AGCH)

BSSMAP: Paging Response

CC: Call Confirmed

(MSISDN)

RR: Paging Type 3

(Paging Cause, TMSI)

(Establishment Cause)

(TMSI, LAI, Classmark)

RR: Cipher Mode Command

(mode = CLEAR)

CC: Alerting

ISUP: Address Complete Message

(Bearer Capabilities)

(Facility, Progress Indicator, User-User Data)

MESSAGE FLOW 3:

Mobile Terminating Call:

MS BSS MSC/VLR PSTN

(MS initiates Call Release by hitting “END” button)

CC: Call Disconnect

ISUP: Answer

ISUP: Release

CC: Call Release Complete

ISUP: Released

CC: Call Connect

(Indicates MSC that the End User has answered the call)

CC: Call Connect Acknowledgment

BSSMAP: Clear Command

ISUP: Release Complete

BSSMAP: Clear Complete

CC: Call Release

(Indicates the phone is ringing)

RR: Channel Release

(Cause, Facility, User- User Data)

MS BSS MSC/VLR PSTN

Active Conversation between Calling and Called Party

()

Delivery Report

Delivery Report

Authentication Request

()

Message Transfer

()

()

Access Request

Access Request

(IMSI, IMEI, TMSI, LAI, MS-

ISDN Number)

(IMSI, IMEI, TMSI, LAI, MS-

ISDN Number)

(RAND)

(RAND)

Authentication Request

Authentication Response

(SRES)

Authentication Response

(SRES)

Cipher mode Command

Cipher mode Command

(mode = CLEAR)

Cipher mode Complete

(mode = CIPHERED) Cipher mode Complete

Forward Short Message

Message Transfer

()

Delivery Report

()

MESSAGE FLOW 4:

MOBILE ORIGINATED SMS:

MS BSS MSC/VLR SMS-IWMSC SMSC

(MS-ISDN Number)

Delivery Report

Delivery Report

Paging Message

Message Transfer

()

Forward Short Message

(IMSI, MS-ISDN No,

destination address user info)

(Paging Info, TMSI)

(Paging Info, TMSI)

Paging Message

Paging Response

(TMSI, LAI)

Paging Response

(TMSI, LAI)

Cipher mode Command

Cipher mode Command

(mode = CLEAR)

Cipher mode Complete

(mode = CIPHERED)

Cipher mode Complete

()

Delivery Report

(MS-ISDN Number)

Message Transfer

()

Authentication Request

(RAND)

Authentication Request

(RAND)

Authentication Response

(SRES)

Authentication Response

(SRES)

Delivery Report Status

MESSAGE FLOW 5:

MOBILE TERMINATED SMS:

MS BSS MSC/VLR GMSC SMSC

RR: Measurement Report

(Intra Frequency Measurements)

Handover Request

(Rank Ordered list of Target BSS) Handover Request

(Cell Area Info, cell identity,

Encryption key, K)

Handover Request Acknowledgment

(Radio Channel Identification)

Handover Command

(New Radio Channel Identification)

Handover Command

(New Radio Channel Identification)

Handover Access

(MS uses the new Radio Channel)

Physical Information

Handover Detected

(Informs MSC about the detection of

Handover)

Handover Completed

(Time Synchronization, Frame Synchronization)

Handover Completed

Release

(Release old radio TCH)

Release Complete

(Release all radio resources with MS)

MESSAGE FLOW 6:

Intra MSC Handover:

MS Serving BSS MSC Target BSS

RR Connection Establishment

Location Update / TMSI Reallocation

Authentication / Ciphering Procedure

Active voice exchange from MS to the Core Network

Intra MSC Handover (Serving BSS to Target BSS within a MSC Area)

RR Connection Establishment

Location Update / TMSI Relocation Procedure

Authentication and Cipher Procedure

Active voice exchange from MS to the Core Network

Inter Handover (Handover between serving BSS to Target BSS within a MSC Area)

RR: Measurement

Report

(Inter Frequency

Measurements)

(Rank ordered list of

Target BSS)

SCCP: Handover

Request

Prepare Handover

Allocate Handover Number (Informs Target MSC

about handover)

(Requests for TMSI)

Send Handover Request

Handover Request

(Allocates new TMSI)

(Cell Area Info, cell

identity, Encryption

key, Ki)

Handover Report

Acknowledge

(Radio Channel

Identification) Prepare Handover

(Acknowledgement)

Send Handover Acknowledgement Handover Command

(New Radio Channel

Identification) Handover Command

(New Radio Channel

Identification)

Handover Access

(MS uses the new radio channel)

Physical Information Message

Handover Detect

Handover Completed

(Time Synchronization, Frame Synchronization)

Handover Completed

MESSAGE FLOW 7:

Inter MSC Handover:

MS Serving BSS Serving MSC Target MSC Target BSS Target VLR

Active voice exchange from MS to the Core Network

RR Connection Establishment

Location Update / TMSI Relocation Procedure

Authentication and Cipher Procedure

Inter Handover (Handover between serving BSS to Target BSS under different MSC Area)

Process Access

Signaling

(Release old radio

TCH)

Release

Release Complete

Send End Signal

(Release all radio

resources with MS) Send End Signal

MS Serving BSS Serving MSC Target MSC Target BSS Target VLR

RRC: Handover Access

Relocation Request

Acknowledgment

Handover Command

RRC: Physical Information

(Information to start using the GSM Radio Link, Channel Descriptions)

Clear Complete

(Indicates about new channel that MS must tune)

RR: Inter System to UTRAN Handover Command

Relocation Detect

RR: Measurement Reporting

(Inter Frequency Measurements, Intra Frequency

Measurements, Traffic Volume Info, QoS) Handover Required

(Cell Identifier List Preferred)

(Indicates that UTRAN can

support relocation request)

(Indicates about new channel

that BSS must tune)

()

(Indicates that the UE has

accessed the target cell)

Relocation Request

(Reason for Relocation,

Target RNC Id, UE Classmark

Info)

RRC: Handover to UTRAN Complete

Relocation Complete

(Indicates that the UE has

accessed the target cell) Clear Command

()

MESSAGE FLOW 8:

INTER-RADIO ACCESS TECHNOLOGY HANDOVER (GSM AREA – 2G TO UMTS AREA – 3G):

MS BTS BSS MSC UTRAN

Active voice exchange from MS to the GSM Core Network

RR Connection Establishment

Location Update / TMSI Relocation Procedure

Authentication and Security Command

Inter – RAT Handover (BSS in MSC of GSM N/W to UTRAN in MSC of UMTS N/W)

Transport Channel Allocation

Active voice exchange from MS to the UMTS Core Network