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laforge, 06/03/2018 10:35 PM
Call Hold SS¶
Call Hold (HOLD) is specified together with Call Waiting (CW).
Relevant Specifications¶
- 3GPP TS 22.083: Call Waiting (CW) and Call Hold (HOLD) supplementary service; Stage 1
- high-level description + definition
- 3GPP TS 23.083: Call Waiting (CW) and Call Hold (HOLD) supplementary service; Stage 2
- contains SDL state diagrams for VLR and MSC
- 3GPP TS 24.010: Supplementary services specification
- 3GPP TS 24.080: supplementary services specification; Formats and coding
- 3GPP TS 24.083: Call Waiting (CW) and Call Hold (HOLD) supplementary service; Stage 3
- contains information on signaling on L3 interface between MS and MSC
Notes¶
- the HOLD state is not a state in the 24.007/24.008 call control state machine, but an auxiliary state machine:
- Idle before/after any HOLD or after HOLD REJECT.
- Hold request HOLD sent but no response yet
- Call Held after successful HOLD operation
- Retrieve request RETRIEVE sent but no response yet
notification of other party¶
The other party is notified if SS-screening != 0:- Facility/Invoke/NotifySS/HOLD
HOLD activation¶
- MS sends HOLD
- MSC responds with HOLD ACK in successful case
- MSC responds with HOLD REJECT in error case (#29: rejected, #50: not subscribed, #69: not implemented, ...)
RETRIEVE activation¶
- MS sends RETRIEVE
- MSC responds with RETRIEVE ACK in successful case
- MSC responds with RETRIEVE REJECT in unsuccessful case
altenating between calls¶
The HOLD/RETRIEVE messages contain the regular CC transaction identifer, which is used to differentiate different calls. You can put one call on hold and subsequently retrieve another.
Updated by laforge about 6 years ago · 2 revisions