Telecom Tutorials by Samir Amberkar

Voice Call continued [Under GSM >> Signaling]

Step 4: Assume now that the number to which call is being made is also a mobile subscriber (same network or different). MSC₂ would be GMSC if call is made to another network (PSTN, CDMA etc.)

MSC1

HLR

VLR2

MAP - Send Routing Info MAP - Provide Roaming Number MAP - PRN response MAP - SRI response

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MSC1

MSC2

ISUP - IAM

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MS1

BTS1

BSC1

MSC1

VLR1

DTAP (Call Progress) RLM (Call Progress) FACCH, CC - Call Progress/Proceed

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MS2

BTS2

BSC2

MSC2

VLR2

MAP - Incoming Call MAP - Page BSSMAP - Paging DCM - Paging Command PGCH, RR - Paging1

1: Paging Message is sent on common Paging Channel (PCH) on all BTSs (cells) in a Location Area in which mobile was registered.

We will continue "Voice Call" in next article.

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

© Copyright Samir Amberkar 2010

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