Call flow oma000003 gsm communication flow

M900/M1800 GSM System Lecturer: Wang Hui OMA000003 GSM Communication Flow

Handover Sequence SMS Sequence Location Update Sequence GSM Basic Call Sequence CONTENT GSM Security Management

GSM Security Management Authentication and Ciphering Sequence TMSI Reallocation Equipment Identification

Authentication Authentication may be executed during setup, location updating and supplementary services

Authentication Sequence KI （ M) KI （ N) IMSI(m) RAND GENERATOR A8 A3 KI(IMSI) IMSIBUFFER RAND RAND RAND RAND KC 1 2 5 KC KC KC SRES SRES SRES SRES TEMP DATA AUC HLR/AUC HLR AUTH REQ RAND KC SRES RAND A8 A3 SRES EQUAL CKSN KC BSS KI(IMSI) VLR SIM RAND 16byte KI 16byte kc 8byte SERS 4byte CKSN low 3bits of 1byte IMSI(n)

Authentication and Ciphering Sequence HLR MS BSS MSC VLR 1 Pre-send Triples to VLR

HLR MS BSS MSC VLR RAND RAND < SDCCH> Authentication and Ciphering Sequence 1 Pre-send Triples to VLR 2 Authenticate Authentication Request

HLR MS BSS MSC VLR RAND RAND < SDCCH> < SDCCH> ( SRES) Authentication and Ciphering Sequence 1 Pre-send Triples to VLR 2 Authenticate Authentication Request 3 Authenticate Response

HLR MS BSS MSC VLR RAND RAND < SDCCH> < SDCCH> ( SRES) Authentication and Ciphering Sequence 1 Pre-send Triples to VLR 2 Authenticate Authentication Request 3 Authenticate Response 4 Start Ciphering

HLR MS BSS MSC VLR 5 Cipher Mode Command Cipher Mode Complete < SDCCH> < SDCCH> 1 Pre-send Triples to VLR 2 Authenticate Authentication Request RAND RAND < SDCCH> 3 Authenticate Response < SDCCH> ( SRES) 4 Start Ciphering Authentication and Ciphering Sequence

TMSI Reallocation MS VLR Location Update Req Location Update Acc TMSI Reallocation Comp (TMSI)

Equipment Identification MS BSS MSC VLR HLR PSTN 1 Equipment ID Request < SDCCH> EIR

MS BSS MSC VLR HLR PSTN 1 Equipment ID Request < SDCCH> 2 ID Response < SDCCH> IMEI) EIR Equipment Identification

MS BSS MSC VLR HLR PSTN 1 Equipment ID Request < SDCCH> 2 ID Response < SDCCH> IMEI) 3 Check IMEI Check IMEI Response EIR Equipment Identification

GSM Basic Call Sequence Mobile to Land Sequence Land to Mobile Sequence Mobile Initiated Call Clearing Sequence

GSM Basic Call Sequence The process for calling MS and called MS are two independent flow. The calling party begins with channel request and ends with TCH assignment competition. In general, the calling party includes following several stages: access process, authentication and ciphering process, TCH assignment process. So, we take the sequence from mobile to land as example, in this sequence, we mainly devote to the calling party.

Mobile to Land Sequence MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN SIGNALING LINK ESTABLISHED PSTN

MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN < SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC PSTN Mobile to Land Sequence

MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN < SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE PSTN Mobile to Land Sequence

MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN < SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE 4 SET-UP < SDCCH> Call Info PSTN SFOC Mobile to Land Sequence

MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN < SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE 4 SET-UP < SDCCH> Call Info 5 EQUIP. ID REQ. PSTN SFOC Mobile to Land Sequence

MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN < SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE 4 SET-UP < SDCCH> Call Info 5 EQUIP. ID REQ. 6 COMPLETE CALL CALL PROCEEDING < SDCCH> PSTN SFOC Mobile to Land Sequence

Mobile to Land Sequence 7 ASSIG. COMMAND < SDCCH> ASSIG. COMPLETE circuit < FACCH> MS BSS MSC VLR HLR PSTN

7 ASSIG. COMMAND < SDCCH> ASSIG. COMPLETE Address Complete(ACM) Alerting circuit < FACCH> Initial and Final Address 8 Message (IFAM) MS hears ring tone from land phone < FACCH> MS BSS MSC VLR HLR PSTN Mobile to Land Sequence

7 ASSIG. COMMAND < SDCCH> ASSIG. COMPLETE Address Complete(ACM) Alerting < FACCH> 9 Answer (ANS)Connect circuit < FACCH> Initial and Final Address 8 Message (IFAM) MS hears ring tone from land phone < FACCH> Ring tone stops MS BSS MSC VLR HLR PSTN Mobile to Land Sequence

7 ASSIG. COMMAND < SDCCH> ASSIG. COMPLETE Address Complete(ACM) Alerting < FACCH> 9 Answer (ANS)Connect 10 Connect Acknowledge < FACCH> circuit < FACCH> < TCH> Initial and Final Address 8 Message (IFAM) MS hears ring tone from land phone < FACCH> Ring tone stops HELLO! MS BSS MSC VLR HLR PSTN BILLING STARTS Mobile to Land Sequence

Question What happens when the calling MS activates the SS of BAOC?

Answer MS BSS MSC VLR HLR 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN < SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE 4 SET-UP < SDCCH> Call Info 5 EQUIP. ID REQ. 6 COMPLETE CALL CALL PROCEEDING < SDCCH> PSTN SFOC Call Barred

GSM Basic Call Sequence For the called party, the flow for the called party begins when MSC sends paging command to the called party, ends when two party start talk. In general, this call flow includes several stages: access process, authentication and ciphering process, TCH assignment process, talk process, release process.

Land to Mobile Sequence MS BSS MSC VLR HLR GMSC ( MSISDN) Initial and Final 1 Address Message PSTN

MS BSS MSC VLR HLR GMSC ( MSISDN) ( MSISDN) ( IMSI) Initial and Final 1 Address Message PSTN 2 Send Routing Info Land to Mobile Sequence

MS BSS MSC VLR HLR GMSC ( MSISDN) ( MSISDN) ( IMSI) ( MSRN) Initial and Final 1 Address Message PSTN ( MSRN) ( MSRN) 2 Send Routing Info 3 Routing Info Ack Initial and Final Address Message Land to Mobile Sequence

MS BSS MSC VLR HLR GMSC ( MSISDN) ( MSISDN) ( IMSI) ( MSRN) ( MSRN) Initial and Final 1 Address Message PSTN ( MSRN) ( MSRN) 2 Send Routing Info 3 Routing Info Ack Initial and Final Address Message 4 Send Info For I/C Call Setup Land to Mobile Sequence

MS BSS MSC VLR HLR GMSC ( MSISDN) ( MSISDN) ( IMSI) ( MSRN) ( MSRN) ( LAI & TMSI) ( TMSI) ( TMSI) Initial and Final 1 Address Message PSTN ( MSRN) ( MSRN) 2 Send Routing Info 3 Routing Info Ack Initial and Final Address Message 4 Send Info For I/C Call Setup 5 Page Paging Request < PCH> Land to Mobile Sequence

6 Channel Request DCCH Assign Signaling Link Established Page Response *Authentication <RACH> <AGCH> <SDCCH> <SDCCH> (TMSI) (TMSI & Status) (Status) CR Land to Mobile Sequence MS BSS MSC VLR HLR GMSC PSTN

6 Channel Request DCCH Assign Signaling Link Established Page Response *Authentication 7 Complete Call Setup <RACH> <AGCH> <SDCCH> <SDCCH> (TMSI) (TMSI & Status) (Status) < TMSI> <SDCCH> CR MS BSS MSC VLR HLR GMSC PSTN Land to Mobile Sequence

6 Channel Request DCCH Assign Signaling Link Established Page Response *Authentication 7 Complete Call Setup 8 Call Confirmation <RACH> <AGCH> <SDCCH> <SDCCH> (TMSI) (TMSI & Status) (Status) < TMSI> <SDCCH> <SDCCH> CR MS BSS MSC VLR HLR GMSC PSTN Ring Tone at the land phone Land to Mobile Sequence

( channel) ( circuit) < FACCH> 9 Assignment Command Assignment Complete Alert < TCH> Address Complete Land to Mobile Sequence MS BSS MSC VLR HLR GMSC PSTN Ring Tone at the land phone

< FACCH> ( channel) ( circuit) < FACCH> 9 Assignment Command Assignment Complete Alert < TCH> < FACCH> 10 Connect Connect ACK ANS < TCH> Hello... Address Complete MS BSS MSC VLR HLR GMSC PSTN Billing starts Ring Tone at the land phone Ringing stops at land phone Subscriber picks up Land to Mobile Sequence

Questions Please give the sequence: 1.The called MS is powered off. 2.The called MS activates the CFU to a PSTN No. 3.The called MS has been barred all incoming call. 4.The Called MS are not known at HLR

1. The called MS is powered off MS BSS MSC VLR HLR GMSC ( MSISDN) ( MSISDN) ( IMSI) Initial and Final 1 Address Message 2 Send Routing Info 3 Routing Info Ack PSTN Subscriber Absent The Land hears the announcement of mobile is powered off Answers

2. The called MS activates the CFU to a PSTN No. (MSISDN) (MSISDN) CFN 4 IFAM Answers MS BSS MSC VLR HLR GMSC PSTN Initial and Final 1 Address Message 2 Send Routing Info 3 Routing Info Ack

Answers 3. The called MS has been barred all incoming call. Call Barred MS BSS MSC VLR HLR GMSC (MSISDN) (MSISDN) Initial and Final 1 Address Message 2 Send Routing Info 3 Routing Info Ack PSTN

Answers 4. The Called MS are not known at HLR Unknown Subscriber MS BSS MSC VLR HLR GMSC (MSISDN) (MSISDN) Initial and Final 1 Address Message 2 Send Routing Info 3 Routing Info Ack PSTN

MS BSS MSC VLR HLR < FACCH> < FACCH> 1 Disconnect PSTN PSTN Release Mobile Release Mobile Initiated Call Clearing Sequence

MS BSS MSC VLR HLR < FACCH> < FACCH> < FACCH> 1 Disconnect PSTN PSTN Release Mobile Release 2 PSTN Release Complete Mobile Release Complete MS-MSC Signalling Released Mobile Initiated Call Clearing Sequence

MS BSS MSC VLR HLR < FACCH> < FACCH> < FACCH> < FACCH> 1 Disconnect PSTN PSTN Release Mobile Release 2 PSTN Release Complete Mobile Release Complete MS-MSC Signalling Released 3 Clear Command Channel Release Mobile Initiated Call Clearing Sequence

Mobile Initiated Call Clearing Sequence < FACCH> <FACCH> 4 DISC UA Clear Complete MS BSS MSC VLR HLR PSTN

Mobile Initiated Call Clearing Sequence < FACCH> <FACCH> 4 DISC UA Clear Complete 5 RLSD Release Complete MS BSS MSC VLR HLR PSTN

Brief Introduction to Location Update Location Update Sequence Several Typical Location Update Sequences

The types of Location Update : Brief Introdution to Location Update Periodic Location Update IMSI Attach/Detach Normal Location Update

Several Typical Location Update Sequences Intra-VLR Location Update Sequence Inter-VLR Location Update Sequence

Intra-VLR Location Update Sequence MS BSS MSC VLR <RACH> 1 Channel Request <AGCH> DCCH Assign HLR Only sent to HLR if this is the first time the MS has Location Updated in this VLR

Intra-VLR Location Update Sequence MS BSS MSC VLR <RACH> 1 Channel Request <AGCH> DCCH Assign 2 Location Update Request <SDCCH> HLR Only sent to HLR if this is the first time the MS has Location Updated in this VLR

Intra-VLR Location Update Sequence MS BSS MSC VLR <RACH> 1 Channel Request <AGCH> DCCH Assign 2 Location Update Request <SDCCH> LAI & TMSI 3 Authentication & Ciphering HLR Only sent to HLR if this is the first time the MS has Location Updated in this VLR

Intra-VLR Location Update Sequence MS BSS MSC VLR <RACH> 1 Channel Request <AGCH> DCCH Assign 2 Location Update Request <SDCCH> LAI & TMSI 3 Authentication & Ciphering 4 Forward New TMSI Location Update Accept < TMSI> <SDCCH> <TMSI> HLR Only sent to HLR if this is the first time the MS has Location Updated in this VLR

Intra-VLR Location Update Sequence MS BSS MSC VLR <RACH> 1 Channel Request <AGCH> DCCH Assign 2 Location Update Request <SDCCH> LAI & TMSI 3 Authentication & Ciphering 4 Forward New TMSI Location Update Accept < TMSI> <SDCCH> <TMSI> 5 TMSI Reallocate Complete TMSI ACK < SDCCH> HLR Only sent to HLR if this is the first time the MS has Location Updated in this VLR

Intra-VLR Location Update Sequence MS BSS MSC VLR <RACH> 1 Channel Request <AGCH> DCCH Assign 2 Location Update Request <SDCCH> LAI & TMSI 3 Authentication & Ciphering 4 Forward New TMSI Location Update Accept < TMSI> <SDCCH> <TMSI> 5 TMSI Reallocate Complete TMSI ACK < SDCCH> 6 Clear Command Clear Complete < SDCCH> < SDCCH> HLR Only sent to HLR if this is the first time the MS has Location Updated in this VLR

Location Update via IMSI Location Update via TMSI Inter-VLR Location Update Sequence

< RACH> 1 Channel Request < AGCH> DCCH Assign MS BSS MSC VLRn HLR VLRo Inter-VLR Location Update Via IMSI

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> MS BSS MSC VLRn HLR VLRo Inter-VLR Location Update Via IMSI LAI & IMSI

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> LAI & IMSI Authentication & Ciphering MS BSS MSC VLRn HLR 3 Authentication Para. Req VLRo . Inter-VLR Location Update Via IMSI

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> LAI & IMSI Authentication & Ciphering MS BSS MSC VLRn HLR 3 Authentication Para. Req 4 Location Update Request Insert Subscriber Data Insert Subscriber Data Ack Location Update accept VLRo Inter-VLR Location Update Via IMSI

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> LAI & IMSI Authentication & Ciphering MS BSS MSC VLRn HLR 3 Authentication Para. Req 4 Location Update Request Insert Subscriber Data Insert Subscriber Data Ack Location Update accept VLRo 5 Cancellocation Cancellocation Ack . Inter-VLR Location Update Via IMSI

6 Forward New TMSI Location Update Accept TMSI Reallocate Complete TMSI ACK Inter-VLR Location Update Via IMSI MS BSS MSC VLRn HLR VLRo

6 Forward New TMSI Location Update Accept TMSI Reallocate Complete TMSI ACK 7 Clear Command Clear Complete Inter-VLR Location Update Via IMSI MS BSS MSC VLRn HLR VLRo

< RACH> 1 Channel Request < AGCH> DCCH Assign MS BSS MSC VLRn HLR VLRo Inter-VLR Location Update Via TMSI

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> MS BSS MSC VLRn HLR VLRo Inter-VLR Location Update Via TMSI LAI & TMSI

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> LAI & TMSI MS BSS MSC VLRn HLR VLRo . Inter-VLR Location Update Via TMSI Authentication & Ciphering 3 Provide Identification provide Identification Ack TMSI&LAIO TMSI,IMSI,KC,R,S)

< RACH> 1 Channel Request < AGCH> DCCH Assign 2 Location Update Request < SDCCH> LAI & TMSI MS BSS MSC VLRn HLR VLRo Inter-VLR Location Update Via TMSI Authentication & Ciphering 3 Provide Identification provide Identification Ack TMSI&LAIO TMSI,IMSI,KC,R,S) 4 Location Update Request Insert Subscriber Data Insert Subscriber Data Ack Location Update accept

Inter-VLR Location Update Via TMSI MS BSS MSC VLRn HLR VLRo 5 Cancellocation Cancellocation Ack .

Inter-VLR Location Update Via TMSI 6 Forward New TMSI Location Update Accept TMSI Reallocate Complete TMSI ACK MS BSS MSC VLRn HLR VLRo 5 Cancellocation Cancellocation Ack .

Inter-VLR Location Update Via TMSI 6 Forward New TMSI Location Update Accept TMSI Reallocate Complete TMSI ACK 7 Clear Command Clear Complete MS BSS MSC VLRn HLR VLRo 5 Cancellocation Cancellocation Ack .

The mobile originated short message transfer procedure is separated from mobile terminated. The basic short message sequence consists of two parts: MO SMS Transfer and MT SMS Transfer. Short Message Sequence

MS BSS MSC VLR Interworking MSC 1 CHANNEL REQUEST <RACH> <AGCH> DCCH ASSIGN SIGNALING LINK ESTABLISHED SC MO SMS Transfer

MS BSS MSC VLR Interworking MSC 1 CHANNEL REQUEST <RACH> <AGCH> DCCH ASSIGN <SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC SC MO SMS Transfer

MS BSS MSC VLR Interworking MSC 1 CHANNEL REQUEST <RACH> <AGCH> DCCH ASSIGN <SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE SC MO SMS Transfer

MS BSS MSC VLR Interworking MSC 1 CHANNEL REQUEST <RACH> <AGCH> DCCH ASSIGN <SDCCH> SIGNALING LINK ESTABLISHED 2 REQ. FOR SERVICE CR CC 3 AUTHENTICATION SET Cipher MODE SC 4 RP_MO_DATA SIF_MO_SMS SIF_MO_SMS-Ack MO SMS Transfer

5 MO_Forward_SM Short_Message MO_Forward_SM_Ack Short_Message_Ack (SC_No.) MO SMS Transfer MS BSS MSC VLR Interworking MSC SC

5 MO_Forward_SM Short_Message MO_Forward_SM_Ack Short_Message_Ack 6 RP_ACK (SC_No.) MO SMS Transfer MS BSS MSC VLR Interworking MSC SC "Send Successfully" is displayed on the mobile

MT SMS Transfer For Forwarding a Short Message For Forwarding Several Short Message

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM MT SMS Transfer (A Message)

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM 2 SIF_MT_SMS Page Page MT SMS Transfer (A Message)

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM 2 SIF_MT_SMS Page Page 3 Paging Response Authentication and Ciphering MT SMS Transfer (A Message)

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM 2 SIF_MT_SMS Page Page Request 3 Paging Response Authentication and Ciphering 4 Short_Message Short_Message_Ack MT_Forward_SM_Ack Short_Message_Ack MT SMS Transfer (A Message)

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM MT SMS Transfer (Several Messages) MT_Forward_SM (The More message To Send Flag is True)

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM MT SMS Transfer (Several Messages) MT_Forward_SM (The More message To Send Flag is True) 2 SIF_MT_SMS Page Paging Request

MS Servicing MSC VLR HLR Gateway MSC SC 1 Short Message SRI_For_SM SRI_For_SM_Ack MT_Forward_SM MT SMS Transfer (Several Messages) MT_Forward_SM (The More message To Send Flag is True) 2 SIF_MT_SMS Page Paging Request 3 Paging Response Authentication and Ciphering

MS Servicing MSC VLR HLR Gateway MSC SC 4 Short_Message Short_Message_Ack MT_Forward_SM_Ack Short_Message_Ack MT SMS Transfer (Several Messages)

MS Servicing MSC VLR HLR Gateway MSC SC 4 Short_Message Short_Message_Ack MT_Forward_SM_Ack Short_Message_Ack MT SMS Transfer (Several Messages) 5 Short_Message MT_Forward_SM MT_Forward_SM (The More message To Send Flag is False) Short_Message_Ack MT_Forward_SM_Ack Short_Message_Ack Short_Message

What is the sequence when the originating subscriber sets the wrong SC No. in the mobile station. Question

MO_Forward_SM Short_Message MO_Forward_SM_Ack Short_Message_Ack RP_ACK (SC_No.) MS BSS MSC VLR Interworking MSC SC "Send Not Successfully" is displayed on the mobile Answer Illegal Subscriber Illegal Subscriber

Handover Sequence Inter - BSS handover sequence Inter - MSC handover sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request TMSI cct. code Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request 4 Handover REQ ACK TMSI cct. code HO Ref. No. Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request 5 Handover Command 4 Handover REQ ACK TMSI cct. code HO Ref. No. HO Ref. No. <FACCH> Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request 5 Handover Command 4 Handover REQ ACK TMSI cct. code HO Ref. No. HO Ref. No. <FACCH> 6 Information Interchange <FACCH> Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request 5 Handover Command 4 Handover REQ ACK TMSI cct. code HO Ref. No. HO Ref. No. <FACCH> 6 Information Interchange <FACCH> 7 Handover Complete Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request 5 Handover Command 4 Handover REQ ACK TMSI cct. code HO Ref. No. HO Ref. No. <FACCH> 6 Information Interchange <FACCH> 7 Handover Complete 8 Clear Command Inter - BSS Handover Sequence

MS oBSS nBSS MSC 1 Periodic Measurement reports <SACCH> 2 Handover required 3 Handover Request 5 Handover Command 4 Handover REQ ACK TMSI cct. code HO Ref. No. HO Ref. No. <FACCH> 6 Information Interchange <FACCH> 7 Handover Complete 8 Clear Command 9 Periodic Meas. reports <SACCH> Inter - BSS Handover Sequence

Inter - MSC Handover Sequence Basic Inter-MSC handover Subsequent Inter - MSC handover

MSCA MSCB VLRB 1 PrepareHandover 2 Allocate HandoverNo. 4 PrepareHandover_Ack 5 Send HO Report_Ack 6 Initial Address Message 3 Send Handover Report Address Completed Answer Basic Inter-MSC handover

MSC/VLRA MSC/VLRB 7 Process Access Signal Send End Signal Forward Access Signal Process Access Signal 8 Clear Forward Release Guard Send End Signal_Ack Basic Inter-MSC handover

MSC/VLRA MSC/VLRB 7 Process Access Signal Send End Signal Forward Access Signal Process Access Signal 8 Release Release Complete Send End Signal_Ack Basic Inter-MSC handover

MSC/VLRA MSC/VLRB HLRA 9 SendAuth. Info Auth Info Update Location InsertSubs.Data InsertSubs.Data_Ack UpdateLocation_Ack Cancellocation Cancellocation_Ack Basic Inter-MSC handover

MSC/VLRA MSC/VLRB HLRA 1 PrepareSubsequentHOV PrepareHandover PrepareHandover PrepareSubsequentHOV 2 Initial and Final Address Message Address Complete Answer 3 RLS RLC Subsequent Inter-MSC handover

MSC/VLRA MSC/VLRB MSC/VLRC Subsequent Inter-MSC handover ForwardAccessSignal 4 ProcessAccessSignal 7 Location Update SendEndSignal_Ack 6 SendEndSignal 5 RLS RLC

MSC/VLRA MSC/VLRB MSC/VLRC Subsequent Inter-MSC handover 5 RLS RLC 7 Location Update SendEndSignal_Ack 6 SendEndSignal 4 ForwardAccessSignal ProcessAccessSignal

MSC/VLRA MSC/VLRB MSC/VLRC 7 Location Update SendEndSignal_Ack 6 SendEndSignal Subsequent Inter-MSC handover 4 ForwardAccessSignal ProcessAccessSignal 5 RLS RLC

MSC/VLRA MSC/VLRB MSC/VLRC 4 ForwardAccessSignal ProcessAccessSignal 5 RLS RLC 7 Location Update SendEndSignal_Ack 6 SendEndSignal Subsequent Inter-MSC handover

Summary 1. GSM Security Mangement 2. GSM Basic Call Sequence 3. Location UpdateSequence 4. SMS Sequence 5. HandoverSequence

Call flow oma000003 gsm communication flow

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