The change is because the requested contact did not respond.
If a one-to-one StreamedMedia call fails because the contact being called did not respond, or the local user did not respond to an incoming call, the connection manager SHOULD indicate this by removing both the SelfHandle and the other contact's handle from the Group interface with reason No_Answer. Documenting existing practice. If a contact is removed from a group for this reason, the equivalent D-Bus error is org.freedesktop.Telepathy.Error.NoAnswer.