The implementation of GetSessionHandlers() in org.freedesktop.Telepathy.Channel.Interface.MediaSignalling interface is missing and has only tp_dbus_g_method_return_not_implemented() call in that.
Problem lead to bug:
Try to initiate a call with some online contact. Which start stream engine, and it calls GetSessionHandlers() on org.freedesktop.Telepathy.Channel.Interface.MediaSignalling interface.
Call may not get established and stream engine exit notmally.
Stream engine crash immediately after GetSessionHandlers() returns.