Inbound call drops after 40 seconds

[cobrapg]

Please help...

I have a remote extension on the public Internet. It's registered correctly and calls ring there with no problems. However, calls from the remote extension drop after about 40 seconds.

The remote extension is a Cisco SPA112 (IP address: x.x.179.178) running the latest firmware.
The internal phone is another Cisco SPA112 on latest firmware.
Running 3CX version 15.5. (IP address: x.x.64.37)

External SIP trunks are working OK and external calls are fine. It's just the remote extension that's acting up.

I ran a packet capture (attached) on the 3CX and noticed ICMP pings starting from the 3CX around the time the call is dropped and shortly after there's a BYE message; so looks like the system drops the call on both ends.



You can also see this in the call flow (also attached).




I did some research and found the SIPPINGPERIOD parameter being a posible culprit but it's set to "0". I haven't made any changes to the default parameters.



I know I'm missing something but I'm not sure where else to look. I can provide more details if necessary.

I will appreciate any and all suggestions.

Thanks for your help.

 

[nub]

calls both to and from the phone drop after 40 seconds?

 

[eddv123]

Cisco phones are not supported remotely unless over VPN, what method are you using to get these working ?

The only time I have known of any sort of related issue is when the router/firewall has SIP ALG enabled still (this is normally a drop after 32 seconds) if you do a Google search you will see lots of responses.

I did some research and found the SIPPINGPERIOD parameter being a posible culprit but it's set to "0". I haven't made any changes to the default parameters.

In the parameters settings its states: Time intervall to poll endpoints with SIP INFO messages, in seconds.

Generally the SIP INFO method is used to carry session control information along the SIP signalling path during an existing session.

An example could be when you are on a call to a bank the session/call is established but you may get asked to type in an account number. SIP INFO can carry the digits you type without changing the SIP session characteristics. I would be keen to know how you think this relates to your issue.

 

[cobrapg]

calls both to and from the phone drop after 40 seconds?

Yes. Though last time I tried it, I placed a call towards the remote extension that when past the 40-second mark and lasted until we decided to hang up. That was only one call though.

When the call is initiated by the remote extension the call always drops on the dot.

 

[cobrapg]

Cisco phones are not supported remotely unless over VPN, what method are you using to get these working ?

The only time I have known of any sort of related issue is when the router/firewall has SIP ALG enabled still (this is normally a drop after 32 seconds) if you do a Google search you will see lots of responses.



In the parameters settings its states: Time intervall to poll endpoints with SIP INFO messages, in seconds.

Generally the SIP INFO method is used to carry session control information along the SIP signalling path during an existing session.

An example could be when you are on a call to a bank the session/call is established but you may get asked to type in an account number. SIP INFO can carry the digits you type without changing the SIP session characteristics. I would be keen to know how you think this relates to your issue.

The method is straight-up SIP and RTP via forwarded ports. I had this working fine before with Asterisk until I decided to jump ship and give 3CX a try a few weeks ago.

SIP ALG is a good one. Didn't think if it. I just disabled it on my firewall. Let's see what happens and I'll update you guys either way.

Thanks.

 

[eddv123]

Check the firewall on that site for SIP ALG it does sound similar.

It's a two-way call so the fact the outbound nature of the call should still be affected by this setting (If it is enabled).

 

[leejor]

Does the remote SPA112 have the same issue, if moved to another site, behind another router?

 

[YiannisH_3CX]

As far as i can see from the provided screenshots the call drops because no ACK message is received after the 200 OK. That indicates that either the phone does not receive the answer of the answer from the phone is not reaching the PBX.