Hold Implementation; Reliability Of Provisional Responses; Transfer; Third Party Call Control - Polycom SIP 2.2.0 Administrator's Manual

Hold Implementation

Note

Reliability of Provisional Responses

Transfer

Third Party Call Control

SIP for Instant Messaging and Presence Leveraging Extensions

The phone supports both currently accepted means of signaling hold.
The first method, no longer recommended due in part to the RTCP problems
associated with it, is to set the "c" destination addresses for the media streams
in the SDP to zero, for example, c=0.0.0.0.
The second, and preferred, method is to signal the media directions with the
"a" SDP media attributes sendonly, recvonly, inactive, or sendrecv. The hold
signaling method used by the phone is configurable (refer to
page A-10), but both methods are supported when signaled by the remote end
point.
Even if the phone is set to use c=0.0.0.0, it will not do so if it gets any sendrecv,
sendonly, or inactive from the server. These flags will cause it to revert to the other
hold method.
The phone fully supports RFC 3262 - Reliability of Provisional Responses.
The phone supports transfer using the REFER method specified in
draft-ietf-sip-cc-transfer-05 and RFC 3515.
The phone supports the delayed media negotiations (INVITE without SDP)
associated with third party call control applications.
The phone is compatible with the Presence and Instant Messaging features of
Microsoft Windows Messenger 5.1. In a future release, support for the
Presence and Instant Message recommendations in the SIP Instant Messaging
and Presence Leveraging Extensions (SIMPLE) proposals will be provided by
the following Internet drafts or their successors:
• draft-ietf-simple-cpim-mapping-01
• draft-ietf-simple-presence-07
• draft-ietf-simple-presencelist-package-00
• draft-ietf-simple-winfo-format-02
• draft-ietf-simple-winfo-package-02
Session Initiation Protocol (SIP)
SIP <SIP/>on
B - 9