GSM Call Flow

TERM

ORIG

GMSC MSC

BSS BSS

BSS BSS

65) DISCONNECT

66) RELEASE

67) DISCONNECT

68) RELEASE COMPLETE

71) CHANNEL RELEASE

69) CLEAR COMMAND

70) RELEASE

72) RELEASE COMPLETE

74) CLEAR COMPLETE

73) CLEAR COMMAND

76) CLEAR COMPLETE

GSM Core Field Operations

75) CHANNEL RELEASE

3) PROCESS ACCESS REQ

MOBILE to LAND

4) AUTHENTICATE 7) AUTHENTICATION RESPONSE 8) SET CIPHERING 13) PROCESS ACCESS ACCEPTED

VLR VLR

14) FORWARD NEW TMSI 17) TMSI ACKNOWLEDGE 19) SEND INFO O/G CALL

ORIG

20) COMPLETE CALL

TERM

MSC MSC

BSS BSS

PSTN PSTN 2) COMPLETE LAYER 3 INFO

1) CM-SERVICE REQ 5) AUTHENTICATION REQ

6) AUTHENTICATION RESPONSE 10) BSS MAP CIPHER MODE COMMAND

9) CIPHER MODE CMD

11) BSS MAP CIPHER MODE COMPLETE

12) CIPHER MODE COMPLETE 15) TMSI REALLOCATION COMMAND 16) TMSI REALLOCATION COMPLETE 18) SET UP

21) CALL PROCEEDING 22) ASSIGNMENT REQUEST 24) INITIAL ADDRESS MSG(IAM) 25) ADDRESS COMPLETE MSG(ACM) 27) ANSWER MSG(ANM)

23) ASSIGNMENT COMPLETE 26) ALERTING 28) CONNECT 29) CONNECT ACK

GSM Core Field Operations

LAND to MOBILE

3) PROVIDE ROAMING # 4) RESULT ROAMING #

VLR VLR

HLR HLR

6) SEND INFO I/C CALL SETUP 7) PAGE MS 10) PROCESS ACCESS REQ 11) AUTHENTICATE

TERM

14) AUTHENTICATION RESPONSE

TERM

15) START CIPHERING 18) ACCESS REQ ACCEPTED

ORIG

19) COMPLETE CALL

GMSC MSC

BSS BSS

2) SEND ROUTING INFO 5) ROUTING INFO ACK

8) PAGING

1) INITIAL ADDRESS MSG(IAM)

9) COMPLETE LAYER 3 INFO 12) AUTHENTICATION REQ 13) AUTHENTICATION RESPONSE 16) CIPHER MODE CMD 17) CIPHER MODE COMPLETE 20) SETUP 21) CALL CONFIRMED 22) ASSIGNMENT REQ 23) ASSIGNMENT COMPLETE 24) A LERTING

25) ADDRESS COMPLETE MSG(ACM)

26) CONNECT 27) CONNECT ACK

GSM Core Field Operations

28) ANSWER MSG(ANM)

PSTN PSTN