When CUBE converts a
delayed offer into an early offer, an incomplete exchange of Format specific
parameters (FMTP) occurs during call establishment, resulting in either the
noninitiation of media transmission or media transmission in a quality that may
not be the best. This is especially a problem in video calls.
To overcome this
situation, midcall renegotiation of capabilities can be configured.
renegotiate [always] command is used to configure this in global
VoIP configuration mode (config-voi-serv) and the
voice-class sip early-offer
forced renegotiate command is dial-peer configuration mode
(config-dial-peer) and voice-class configuration mode (config-class).
Figure 2. MidCall
Renegotiation of Capabilities
renegotiate command triggers a delayed-offer RE-INVITE if the
negotiated codecs are one of the following:
- aaclld—Audio codec AACLD
- h263—Video codec H263
- h263+—Video codec H263+
- h264—Video codec H264
- mp4a—Wideband audio codec
renegotiate always command always triggers a delayed-offer
RE-INVITE. This option can be used to support all other codecs.