SOLVED Polycom doesn't hang up

[roger_roger]

When calling a Polycom phone and the calling party hangs up before the call is answered, the Polycom does not acknowledge the 487 termination request and continues to ring. If, on another call, it is answered and the calling party hangs up, the Polycom does hang up.

This doesn't appear to be a network issue as a Yealink phone on the same network behaves properly. What could be causing this?

 

[Adrian Fretwell]

Comparing a couple of packet traces Yealink vs polycom may help you work out what is happening.

A BYE is effectively an in-dialogue request because it has a to tag where as a CANCEL does not, it may or may not be significant in your case.

I have found also that Yealink phones can be very tolerant of malformed packets.

 

[roger_roger]

Comparing a couple of packet traces Yealink vs polycom may help you work out what is happening.

A BYE is effectively an in-dialogue request because it has a to tag where as a CANCEL does not, it may or may not be significant in your case.

I have found also that Yealink phones can be very tolerant of malformed packets.

On IRC chat, I'm told it is a NAT and/or ALG issue with the Comcast router

 

[Adrian Fretwell]

On IRC chat, I'm told it is a NAT and/or ALG issue with the Comcast router

It does sound like a NAT related issue, I always disable ALG or SIP helper on the router if I can. Sometimes just so I can understand exactly what the router is doing, I will packet capture on the LAN and WAN side simultaneously so I can see what changes have been made to Contact headers, Via headers and SDP bodies etc.

 

[roger_roger]

Unfortunately, ALG cannot be disabled on a Comcast router. We may have to get our own router and use the Comcast router in bridge mode.

 

[benw]

if your on fs 1.8.5 there is a known nat issue and i have seen this popup on polycoms but randomly

 

[roger_roger]

I'm still on 1.8.3 - thanks

 

[roger_roger]

I enabled SIP force contact and that has fixed the issue; the phones hang up properly now.