Internal calls not coming through to 3cx windows client

[Tiby Samuel]

Hello,

We have an issue where the internal calls are not showing up on a 3cx client in Windows. The user is able to make external calls and internal calls but unable to receive internal calls.

I have noticed the below error in the activity log where 3040 is the extension number.

01/04/2018 2:05:44 PM - Exception: ParseException E:\root15_5_sp2\Sources\3rdParty\Resiprocate\rutil/ParseBuffer.hxx:230, Parse failed unexpected eof in context: 3040 ^ @ E:\root15_5_sp2\Sources\3rdParty\Resiprocate\rutil/ParseBuffer.hxx:230

These are the other messages:

01/04/2018 2:05:44 PM - [CM503016]: Call(C:4263): Attempt to reach <sip:[email protected]:5060> from Extn:2010 has failed. Reason: Busy
01/04/2018 2:05:44 PM - L:4263.1[Extn:2010] forwards call from Extn:3040 to EndCall:EndCall based on rule Fwd[Available/NoAnsw]
01/04/2018 2:05:44 PM - [Flow] Endpoint Extn:3040 forwarding rule Fwd[Available/NoAnsw] on reason No Answer is set to 'EndCall'
01/04/2018 2:05:44 PM - L:4263.1[Extn:2010] failed to reach Extn:3040, reason No Answer

The 3CX client doesn't show up with an incoming call and I think the system assumes the client is busy and rejects the call after 20 secs.

Any help is greatly appreciated.

Please let me know if you need any further information.

Thank you!

Tiby

 

[NickD_3CX]

Is the 3CX Client installed on a PC that is on the same LAN as the 3CX server or is it at another location, connecting back to the server over the Internet?

 

[Tiby Samuel]

It is on a different LAN on another location connecting back to the server over the internet.

The desk phones at this different LAN location are all working fine. It is just the 3cx client installed on Windows machines.

Thank you for looking into this.

 

[NickD_3CX]

The first thing to always check when talking about remote extension of any sort is "Did the Firewall Checker pass?". Regardless of whether some phones work and others not, I always suggest doing this once to rule out any FW issues and move forward.
This can be done form the Dashboard --> "Firewall Check" option.

If everything passes, especially port 5090 (make sure on FW its open for both UDP and TCP), go to the Extension Settings of one of the 3CX Clients that isn't working, go to the "Phone Provisioning" tab, in the drop-down select the "3CX Client", and make sure the "Use 3CX Tunnel for remote connections (3CX Client only)" is checked.
If it wasn't, check it and resend a Welcome Email to that extension and have the issue reload it into the client.

General rule, in order for a 3CX Client, regardless of platform, to work reliably when remote, it must be using the 3CX Tunnel.

 

[Tiby Samuel]

The firewall test says ok and is showing green. We had tested this before as this issue has been going on for a while now. The port 5090 is open for both UDP and TCP on the firewall.

"Use 3CX Tunnel for remote connections" was checked for the client. However, for testing purpose, I had unticked this yesterday. So now, I have ticked it back, resend the welcome email but still when I dial extension 3040, it doesn't show any notification for an incoming call.

Is there anything else we can try?

 

[NickD_3CX]

Is this only happening to a single extension at this site or is it more that are experiencing this?

Could you also make sure that the 3CX Client is not in CTI mode? Under the Extensions Profile Status there is an option.

 

[Tiby Samuel]

This is happening to any extension on this site. I am sure about 2 extensions but can confirm others too. I am in the process of installing and testing on other machines.

I can see 3CX client is in softphone mode.

 

[NickD_3CX]

So just to clarify this, it is ALL 3CX client at this site having this problem, but 3CX Client at other sites connecting to the same 3CX Server don't have this problem right?

 

[Tiby Samuel]

We have got 3 sites in total connected over site-to-site VPN. Say A,B & C.

Server is on site A. The 3CX client works fine in 2 machines at this site.
We have this issue at site B.
We do not need to use 3CX client in site C so we haven't tested it on site C.

The desk phones are working fine on all the three sites.

 

[NickD_3CX]

So the phones at site B are not connecting back to the server over the public internet, they are going over the VPN Tunnel you have established (or at least they should be from your description).

The next troubleshooting step I would suggest is to now try and check what is going on using Wireshark to do a packet trace and check if the INVITE message is being delivered to the extension and site B, and more importantly if it is sending back a response.

 

[Tiby Samuel]

The first thing to always check when talking about remote extension of any sort is "Did the Firewall Checker pass?". Regardless of whether some phones work and others not, I always suggest doing this once to rule out any FW issues and move forward.
This can be done form the Dashboard --> "Firewall Check" option.

If everything passes, especially port 5090 (make sure on FW its open for both UDP and TCP), go to the Extension Settings of one of the 3CX Clients that isn't working, go to the "Phone Provisioning" tab, in the drop-down select the "3CX Client", and make sure the "Use 3CX Tunnel for remote connections (3CX Client only)" is checked.
If it wasn't, check it and resend a Welcome Email to that extension and have the issue reload it into the client.

General rule, in order for a 3CX Client, regardless of platform, to work reliably when remote, it must be using the 3CX Tunnel.

We have run the firewall checker and found 2 errors related to sip. We followed the link there on "how to resolve this" and got a suggestion to disable "inspect sip" in the firewall. We have done this and all is working fine now. Thank you Nick for all your help!