> Arjun wrote: > > The MOH uses the OPTIONs as a keepalive mechanism, to make sure the > > dialog is still active. What's the interval between the > OPTIONs? The > > default I believe is 5mins. >
The traces we were looking at had three OPTIONs messages back-to-back. Given their frequency and what Arjun is saying, it does not sound like the OPTION messages we saw were the MOH 'keep alive' messages. > Just to confirm, this is done to clean up dangling MOH dialogs? > > The reason I ask is that the XTRN-419 problem is that the > Polycom does not send BYE when taking the call off hold, and > therefore leaves the MOH dangling. > > If sipXpark cleans up these dialogs promptly, then the impact of > XTRN-419 is much less severe. There is another dimension to the problem which goes beyond the inefficient use of resources. Basically, when a MOH session is left dangling, the phone that was involved in that MOH continues to be hammered with RTP packets. If that phone takes part in a new call before the dangling MOH is cleaned up then that phone will be subjected to two RTP streams (the dangling MOH stream and the legitimate one from the far-end) and in the case of Polycom, because of the way it re-uses the same RTP port across media sessions, it will receive two different RTP streams on its media port which will confuse it and will result in silence being played out. _______________________________________________ sipx-dev mailing list [email protected] List Archive: http://list.sipfoundry.org/archive/sipx-dev Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-dev
