| The first very important question is how are you on patches? Check the 1000s, the sig servers, media / ITG cards etc. IP on the Nortel stuff is very patch intensive, if you don't have access to the MPL then have a vendor run a patch audit for you.
The next question after this is how are you on resources (media ports etc) and is there any remote chance that some of the RTP ports are being blocked in the network somewhere or that a routing mechanism is failing; RTP port allocation is always within the same range of ports but if you have 1 or 2 that are being blocked it will cause all sorts of random speech path issues. Bear in mind that call signalling and RTP take place on different ports - it is posible to block all of the RTP ports and deny routing between subnets and the phone will still ring... there just won't be any speech path.
If it were me I would try to get a call in progress that has the one way speech path and start sniffing out in the network starting with the system that can't be heard and checking for an RTP stream and work out from there. |