Note: As soon as an entity sends a session-terminate action, it MUST consider the session to be in the ENDED state (even before receiving acknowledgement from the other party). If the terminating entity receives additional Jingle-related IQ-sets from the other party after sending the session-terminate action, it MUST reply with an <unknown-session/> error.
-Unfortunately, not all sessions end gracefully. In applications of Jingle that also involve the exchange of presence information, receipt of &UNAVAILABLE; from the other party MAY be considered a session-ending event. However, in this case there is nothing for the party to acknowledge.
+Not all Jingle sessions end gracefully. When the parties to a Jingle session also exchange XMPP presence information, receipt of &UNAVAILABLE; from the other party SHOULD be considered a session-ending event that justifies proactively sending a session-terminate action to the seemingly unavailable party -- if, that is, no other communication has been received within 5 or 10 seconds from the seemingly unavailable party in the form of XMPP signalling traffic, connectivity checks, or continued media transfer.
At any point after initiation of a Jingle session, either entity MAY send an informational message to the other party, for example to inform the other party that a device is ringing.