Telecom Tutorials by Samir Amberkar

Inside MS Layer 3 - Call Release [Under GSM >> Signaling]

Let us have a brief look at primitive interfaces inside MS Layer 3 for Call Release.

1) Call disconnected by MS

MN

CC

MM

RR

AIR

User hangs up the call. Adaptation layer (MN) receive AT command, ATH. MNCC-DISC-REQ CC/DISCONNECT CC/RELEASE MNCC-REL-IND Adaptation layer informs release to user. CC/RELEASE COMPLETE MMCC-REL-REQ CC released. MM wait for RR release. CC do not need confirmation as it is already released. RR/CHAN REL RR-REL-IND L2 disconnect L2 disconnect with DISC/UA frame.

2) Call disconnected from other party

MN

CC

MM

RR

AIR

Other party has disconnected the call. CC/DISCONNECT MNCC-DISC-IND CC/RELEASE MNCC-REL-REQ Adaptation layer informs user about call disconnection. MNCC-REL-CNF MMCC-REL-REQ CC released. MM request RR release. RR-REL-REQ RR/CHAN REL L2 disconnect L2 disconnect with DISC/UA frame.

References: GSM Networks book by Heine, Signaling diagrams from 24.007/24.008 (R99)

Copyright © Samir Amberkar 2010

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