3Com VCX V7122 SIP VoIP Gateway User Manual152The 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 totransfer 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 onlyskipping the consultation stage).The VCX V7122 gateway doesn't initiate call transfer. It only can respond to call transferrequest.TDM TunnelingThe VCX V7122 TDM Tunneling feature allows you to tunnel groups of digital trunk spans ortimeslots (B-channels) over the IP network. TDM Tunneling utilizes the internal routingcapabilities of the VCX V7122 (working without Proxy control) to receive voice and datastreams from TDM (1 to 16 E1/T1/J1) spans or individual timeslots, convert them intopackets 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 VCXV7122.ImplementationWhen TDM Tunneling is enabled (‘EnableTDMOverIP’ is set to 1 on the originating VCXV7122), 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 thatthe call originates from. The IP to Trunk Group routing table is used to define the destinationIP address of the terminating VCX V7122. The terminating VCX V7122 gatewayautomatically answers these calls if its E1/T1 protocol is set to ‘Transparent’(ProtocolType = 5) and parameter ‘ChannelSelectMode = 0’ (By Phone Number).
