Call Forward Bridge Mode; Call Transfer Bridge Mode; Register Enhancement - Linksys SPA9000 Administrator's Manual

Chapter 4 Configuring SPA9000 Features

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.
The <CWFD Bridge Mode> parameter has two possible values:
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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.
The <XFER Bridge Mode> parameter has three possible values:
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REGISTER Enhancement

This enhancement is related to how the SPA retries the SIP REGISTER operation when the current
REGISTER has failed.
In previous versions of the SPA9000, three parameters, available on the SIP tab of the administration
web server, have been used to control the interval between retries after a REGISTER failure:
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Document Version 3.01
none—Do not bridge forwarded calls (use the normal REFER method)
all—Bridge all forwarded calls
none —Do not bridge call transfer (use the normal REFER method)
all —Bridge all call transfer
all except same line—Bridge call transfer only if it is between two different line interfaces
<Reg Retry RSC> = A comma separated list of failure register response codes. When one of these
codes occurs, the SPA9000 waits for a duration equal to the number of seconds defined in the <Reg
Retry Invl> parameter.
For other failure codes, the SPA9000 uses the value specified in the <Reg Retry Long Intvl>
parameter. Note that if the REGISTER request times out waiting for a response, or if the request
encounters an ICMP error, the SPA9000 always uses the value specified in the <Reg Retry Intvl>
parameter
<Reg Retry Intvl> = Retry interval in seconds
<Reg Retry Long Intvl> = Long retry interval in seconds
Enhancements in Release 5.1
Linksys SPA9000 Administrator Guide
4-33