When Siskin receives a Jingle session-initiate that does not contain a <group> node, it just terminates the session. Siskin even requires a <group> node in an audio-only call that only has one content, and thus nothing can be grouped.

However, groups are not required to establish calls. When sending an empty or invalid group, audio and video calls are established just fine. Thus, please remove the requirement of having some sort of group node in the session-initiate.