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"
• 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.