Hold Implementation

The phone supports two currently accepted means of signaling hold.

The phone can be configured to use either hold signaling method. The phone supports both methods when signaled by the remote endpoint.

Table 1. Supported Hold Methods

Method

Notes

Signal the media directions with the "a" SDP media attributes sendonly, recvonly, inactive, or sendrecv.

Preferred method.

Set the "c" destination addresses for the zmedia streams in the SDP to zero. For example, c=0.0.0.0

No longer recommended due to RTCP problems associated with this method.

Receiving sendrecv, sendonly, or inactive from the server causes the phone to revert to the other hold method.