Call Hold And Retrieve; Consultation / Alternate - AudioCodes MP-124 User Manual

SIP User's Manual

7.13.1 Call Hold and Retrieve

7.13.2 Consultation / Alternate

Version 5.2
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Notes:
•
All call participants must support the specific supplementary service that
is used.
•
When working with certain application servers (such as BroadSoft's
BroadWorks) in client server mode (the application server controls all
supplementary services and keypad features by itself), the gateway's
supplementary services must be disabled.
Initiating Hold / Retrieve:
Active calls can be put on-hold by pressing the phone's hook-flash button.
The party that initiates the hold is called the holding party; the other party is called the
held party.
After a successful Hold, the holding party hears a Dial Tone (HELD_TONE, defined in
the gateway's Call Progress Tones file).
Call retrieve can be performed only by the holding party while the call is held and
active.
The holding party performs the retrieve by pressing the hook-flash.
After a successful retrieve, the voice is connected again.
Hold is performed by sending REINVITE message with IP address 0.0.0.0 or
a=sendonly in the SDP according to the paranmeter HoldFormat.
Receiving Hold / Retrieve
When an active call receives Re-INVITE message with either the IP address 0.0.0.0 or
the 'inactive' string in SDP, the gateway stops sending RTP and plays a local Held
Tone.
When an active call receives Re-INVITE message with 'sendonly' string in SDP, the
gateway stops sending RTP and listens to the remote party. In this mode, it is
expected that on-hold music (or any other hold tone) is to be played (over IP) by the
remote party.
The consultation feature is relevant only for the holding party (applicable only to the
FXS module).
After holding a call (by pressing hook-flash), the holding party hears a dial tone and
can now initiate a new call, which is called a consultation call.
While hearing a dial tone, or when dialing to the new destination (before dialing is
complete), the user can retrieve the held call by pressing hook-flash.
The held call can't be retrieved while Ringback tone is heard.
After the consultation call is connected, the user can switch between the held and
active call by pressing hook-flash.
357
7. Telephony Capabilities
September 2007