Accommodating m=line Omissions During Call Setup

The Oracle® Enterprise Session Border Controller (E-SBC) can accommodate for signaling from non-compliant endpoints that omit mlines during SDP negotiation. You can configure the fix-missing-mlines option in sip-interface to make the E-SBC allow the call to proceed despite the missing lines.

In SDP, an M line specifies the media endpoints are negotiating for a call. To complete the negotiation, the answer should contain exactly the same number of m= lines as the offer, as specified by RFC 3264. This allows for streams to be matched up based on their order. For example, if an SDP offer contains two m= lines, the answer should also contain two m= lines.

When processing an answer the E-SBC normally checks the offer/answer pair to ensure the same number of media descriptors are present in the offer and answer SDPs. To work around the non-compliant endpoint, you can enable the fix-missing-mlines option under the media-manager configuration. The fix-missing-mlines option removes this check.

The syntax for enabling the fix-missing-mlines option in sip-interface follows.

ORACLE(sip-interface)# options + fix-missing-mlines=yes