...
Feature 1393 multiple m-line supports RFC 3264 (Offer/Answer Model with SDP) and allows the IMG to select an acceptable media stream from a valid SIP offer containing multiple media streams (m-lines). The answer or response will contain the media streams that are accepted and will also contain the media streams that are rejected. The rejected media streams in the answer will have the media port number set to zero in the m-line. The IMG accepts a minimum of 1 m-line and a maximum of 4 m-lines and by default, accepts the first matching media stream with at least one media format. The feature is enabled by default and no configuration is required for the feature to function. See below for more information on F-1393.
Related Topics:
IMG 1010 - SIP Profile - 10.5.3
Diagram:
...
Examples:
Below are examples of how IMG would react to SIP offers with different types of Media Descriptors. (Ex: Audio, Video, Fax). See Additional Information below explaining how the IMG selects which Media Descriptor.
...