Phantom calls to Attendants running Avaya Soft consoles

[Me10]

We have installed Avaya CM5.0 S8500 at a Core site in Sydney, with LSP sites running a mix of S8300/G350/G700 in Melbourne, Adelaide, Brisbane, Hong Kong, San Fran and Abu Dhabi.
We have set up 2 x Attendant softconsole positions at Brisbane, Melbourne and Adelaide sites. They are running Avaya Softconsole 1.5 with 1.5.3 and 1.5.4 patches applied.

Since installation all sites with Softconsole have had random phantom calls either:
displaying "Unknown Caller", and on answering the call the attendants hear nothing.
Or alternativley simply "ringing" (playing the incoming call .wav file) with nothing shown on the Softconsole display and no call showing in the attendant queue.

Anyone encountered similar or suggest where to look ??

 

[Blight]

Do you have any sat com's tied to your system? When I was working on a system that dealt with completely Sat communication(remote military setup), this was a common problem. There is/was no fix to it, and the best fix I found was to busy the line out for a few minutes and release it. This SOMETIMES caused it to go away... This was the only time I've ever seen a significant amount of ghost ringing on a daily basis...

 

[Me10]

Thanks Blight,
but we don't have any sat comms, this is a fairly vanilla IP solution.
We think it may actually be the "Off Hook Alerting" which was set to 10 secs. We have extended this to 3000 secs and now currently monitoring.