Cisco Systems manual Call Transfer Support on SPA9000, Call Forward Bridge Mode

Configuring Phone Lines and Calling Routing Behavior	4
Call Transfer Support on SPA9000

Call Transfer Support on SPA9000

You can configure the bridge mode for call forward and call transfer.

Call Forward Bridge Mode

The normal way of performing the call forwarding operation is for the SPA9000 to send a (blind) SIP REFER to the calling device to let it contact the target number directly. It then drops out of the call completely. This requires the calling device to understand the SIP signaling involved and the operation permitted by the underlying service provider. The SPA400 cannot handle this operation.

With bridging, the SPA9000 maintains two separate call legs throughout the call: one with the caller and one with the call forward target. The two call peers connect only with the SPA9000, while the SPA9000 acts as a proxy for the RTP packets exchanged between the two parties. On the Voice > Line N page, Proxy and Registration section, the CWFD Bridge Mode field has two possible values:

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none—Do not bridge forwarded calls (use the normal REFER method)

all—Bridge all forwarded calls

Call Transfer Bridge Mode

The normal way of performing this operation is for the SPA9000 to send a SIP REFER method to the calling device to let it contact the transfer target directly. The SPA9000 then drops out of the call completely. This requires the calling device (the transferee) and the target device to understand the SIP signaling involved and the operation permitted by the underlying service providers. Note that the call legs with transferee and the transfer target might be with different ITSP. The SPA400, for instance, cannot handle this operation.

With bridging, the SPA9000 maintains two separate call legs throughout the call: one with the transferred call and one with the transfer target. The two call peers connect only with the SPA9000, while the SPA9000 acts as a proxy for the RTP packets exchanged between the two parties. On the Voice > Line N page, Proxy and Registration section, the XFER Bridge Mode field has three possible values:

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none: Do not bridge call transfer (use the normal REFER method)

all: Bridge all call transfer

all except same line: Bridge call transfer only between different line interfaces

SPA9000 Voice System Administration Guide 84