Tdm Tunneling; Implementation - 3Com VCX V7122 User Manual

The common way to perform a consultation transfer is as follows:
In the transfer scenario there are three parties:
Party A - transferring, Party B – transferred, Party C – transferred to.
A Calls B.
B answers.
A presses the hookflash and puts B on-hold (party B hears a hold tone).
A dials C.
After A completes dialing C, A can perform the transfer by on-hooking the A phone.
After the transfer is completed, B and C parties are engaged in a call.
The transfer can be initiated at any of the following stages of the call A to C:
Just after completing dialing C phone number - Transfer from setup.
While hearing ring back – Transfer from alert.
While speaking to C – Transfer from active.
Blind transfer is performed after we have a call between A and B, and A party decides to
transfer the call to C immediately without speaking with C.
The result of the transfer is a call between B and C (just like consultation transfer only
skipping the consultation stage).
The VCX V7122 gateway doesn't initiate call transfer. It only can respond to call transfer
request.

TDM Tunneling

The VCX V7122 TDM Tunneling feature allows you to tunnel groups of digital trunk spans or
timeslots (B-channels) over the IP network. TDM Tunneling utilizes the internal routing
capabilities of the VCX V7122 (working without Proxy control) to receive voice and data
streams from TDM (1 to 16 E1/T1/J1) spans or individual timeslots, convert them into
packets and transmit them automatically over the IP network (using point-to-point or point-to-
multipoint gateway distributions). A VCX V7122 opposite it (or several VCX V7122 gateways,
when point-to-multipoint distributions is used) converts the IP packets back into TDM traffic.
Each timeslot can be targeted to any other timeslot within a trunk in the opposite VCX
V7122.

Implementation

When TDM Tunneling is enabled ('EnableTDMOverIP' is set to 1 on the originating VCX
V7122), the originating VCX V7122 automatically initiates SIP calls from all enabled B-
channels belonging to the E1/T1/J1 spans that are configured with the 'Transparent'
protocol. The called number of each call is the internal phone number of the B-channel that
the call originates from. The IP to Trunk Group routing table is used to define the destination
IP address of the terminating VCX V7122. The terminating VCX V7122 gateway
automatically answers these calls if its E1/T1 protocol is set to 'Transparent'
(ProtocolType = 5) and parameter 'ChannelSelectMode = 0' (By Phone Number).
152 3Com VCX V7122 SIP VoIP Gateway User Manual