'3CX Phone System is unreachable' when call ends

[adamwells]

Hi

Have about 30 extensions set up, with some users using 3CX Phone. We've been noticing the following error appearing on 3CX Phone when a call somewhere in the office ends.

'3CX Phone Sysem is unreachable. 3CXPhone will try to reconnect automatically. Please wait.'

It will reconnect and then continue to work fine.

This is a new issue and as far as I know nothing has changed, although we did put the server onto a new subnet.

Any help appreciated

Thanks

 

[NickD_3CX]

This usually means what the message implies, that the connection between the client and the server is lost.

Are these local extensions? Also did you choose "Split DNS" during the initial setup of 3CX Phone System?

 

[adamwells]

Thanks for the reply.

Yes - all our extensions are local. I did not set up the system so I am not sure, but as I say this problem has just appeared long after the initial setup.

I ran a ping -t to the 3CX server whilst this happened and my connection was fine.

 

[NickD_3CX]

Try opening the Provisioning File you used to provision the 3CX Phone app with a text editor, and find the line towards the end of the file that starts with the tag <MyPhoneServerLocalSSLAddr>, the URL found there, is it the same as the the one in tag <MyPhoneServerPublicSSLAddr>.

If they are the same most likely you used Split DNS.

Now if on the machine where the 3CXPhone is located you open a browser and copy-paste the <MyPhoneServerLocalSSLAddr> URL into the browser, do you see something?

 

[adamwells]

Hi

The addresses are not the same, no. Local SSL Address is https: //servername.domain.local:5001/MyPhone/MPWebService.asmx

Public SSL is the same but our public IP replaces the server name.

Accessing the link does not give me anything.

Thanks for your help so far

 

[NickD_3CX]

If the Local SSL link from a machine running 3CXPhone does not show anything in a browser, then the 3CXPhone app is not retrieving the Presence from that link (which is should be). If a had to guess, in this case your 3CXPhone client is trying the Public SSL link so it is getting the Presence information form a hairpin redirection on the Firewall, and a lot of Firewall don't like that very much, which might be causing those disconnections you are getting.

On the machine running the 3CXPhone open a cmd and type: nslookup servername.domain.local
Generally this should return the 3CX Servers IP Address, if it doesn't you have to fix the Internal DNS the PCs are using.

 

[adamwells]

Hi Nick,

Some more info regarding this issue. I'll give you a brief overview of our setup as this may help.

We use 4 terminal servers located offsite, we have a VPN to access these.

I have just tried accessing the https://servername.domain.local:5001/My ... rvice.asmx directly from one of the terminal servers, and I get to a MPWebService page. If I run the nslookup from here also, I get the DC Server + DC IP listed and 3CX Server + IP, so it appears DNS is working as expected.

Thanks!