[asterisk-users] Ghost ringing

[jfratantoni at iswan.net]

We are having the strangest issue that I have seen for some time. A
customer of ours with Polycom phones (4x ip335, 2x ip550) will
occasionally (maybe 1 in 50 calls) hear ringing on the line along with the
other party. It has happened on both incoming and outgoing calls across
apparently all of the phones. We use ip550 in our office with Asterisk and
have never had such a problem (we run the same firmware as well, although
their hardware is newer). It can be fixed if the person using the phone
puts the other person on hold and then takes them off hold. They have just
been doing this by double pressing hold so the other party doesn't even
realize it. Everything is connected to an on-net Asterisk box. We have
sniffed SIP traffic and haven't found anything out of the ordinary, in
fact, the RTP data doesn't appear to contain the ringing even though it is
audible on the phone.

Any thoughts? Anyone ever experience any similar issues?

Thanks much in advance,
Joe