Mobile Originating Call (MOC): Call setup is initiated by MS
- Channel Request: The MS requests for the allocation of a
dedicated signaling channel to perform the call setup.
- After allocation of a signaling channel the request for MOC call
setup, included the TMSI (IMSI) and the last LA1, is forwarded
to the VLR
- The VLR requests the AC via HLR for Triples (if necessary).
- The VLR initiates Authentication, Cipher start, IMEI check
(optional) and TMSI Re-allocation (optional).
- If all this procedures have been successful, MS sends the Setup
information (number of requested subscriber and detailed service
description) to the MSC.
- The MSC requests the VLR to check from the subscriber data
whether the requested service an number can be handled (or if
there are restrictions which do not allow further proceeding of the
- If the VLR indicates that the call should be preceded, the MSC
commands the BSC to assign a Traffic Channel (i.e. resources for
speech data transmission) to the MS
- The BSC assigns a Traffic Channel TCH to the MS
- The MSC sets up the connection to requested number (called