OMA000003 GSM Communication Flow GSM System OMA000003 GSM Communication Flow Lecturer: Wang Hui

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

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

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

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

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

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

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

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

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

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

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

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 PSTN 1 CHANNEL REQUEST < RACH> < AGCH> DCCH ASSIGN SIGNALING LINK ESTABLISHED

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

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

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

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

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

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

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

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

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

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

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

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 PSTN Initial and Final 1 Address Message ( MSISDN)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Short Message Sequence 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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Subsequent 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 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 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 4 ProcessAccessSignal ForwardAccessSignal 5 RLS RLC 6 SendEndSignal SendEndSignal_Ack 7 Location Update

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

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

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

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