Relevant Parameters; Working With Supplementary Services; Call Hold And Retrieve Features; Call Transfer - 3Com VCX V7122 User Manual

To enable PSTN fallback, assign the IP address of the gateway itself as an alternative route
to the desired prefixes. Note that calls (now referred to as IP to Tel calls) can be re-routed to
a specific trunk group using the Routing parameters.

Relevant Parameters

The following parameters (described in
Alternative Routing mechanism:
AltRoutingTel2IPEnable
AltRoutingTel2IPMode
IPConnQoSMaxAllowedPL
IPConnQoSMaxAllowedDelay

Working with Supplementary Services

The VCX V7122 SIP gateway supports the following supplementary services:
Hold / Retrieve
Transfer
Call Forward (doesn't initiate call forward, only responds to call forward request)
Call Waiting
VCX V7122 SIP users are only required to enable the Hold and Transfer features. The call
forward (supporting 30x redirecting responses) and call waiting (receive of 182 response)
features are enabled by default. Note that all call participants must support the specific used
method.

Call Hold and Retrieve Features

The party that initiates the hold is called the holding party, the other party is called the
held party. The VCX V7122 gateway can't initiate the hold, but it can respond to hold
request, and as such it is a held party.
After a successful hold, the held party should hear HELD_TONE, defined in gateway's
Call Progress Tones file.
Retrieve can be performed only by the holding party while the call is held and active.
After a successful retrieve the voice should be connected again.
The hold and retrieve functionalities are implemented by Reinvite messages. The IP
address 0.0.0.0 as the connection IP address or the string "a=inactive" in the received
Reinvite SDP cause the gateway to enter Hold state and to play held tone (configured in
the gateway) to the PBX/PSTN. If the string "a=recvonly" is received in the SDP
message, the gateway stops sending RTP packets, but continues to listen to the
incoming RTP packets. Usually, the remote party plays, in this scenario, Music on-hold
(MOH) and the VCX V7122 forwards the MOH to the held party.

Call Transfer

There are two types of call transfers:
Consultation Transfer
Blind Transfer
3Com VCX V7122 SIP VoIP Gateway User Manual
Table 28 on page 119) are used to configure the
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