Phone app works on cell & sometimes not at all on Wi-Fi

[stevehensyel]

Our IT dept has been experiencing this for quite a while now. The 3CX app works better on cell service and it is intermittent / not at all when connected on our Wi-Fi. When connected to wi-fi my phone will ring but I am not always able to answer the call. If I am on wi-fi it will not bring up the complete contacts directory or show recent calls, but if I turn off the Wi-Fi on my phone it does. my phone service is Google-Fi and my phone is an Pixel 5a. Other people in our IT dept. have the same issue with other phones and carriers.

 

[SteveITS]

Does it work on other (e.g. your home) Wi-Fi? If it's just internal to the office, it could be DNS resolution or NAT reflection, etc. issues.

 

[stevehensyel]

Good question and I will have to check to be sure but I believe it works fine on my home Wi-Fi. We have multiple offices around the city but connect to the same SSID at all offices and it acts the same way. Where would we begin to check DNS or NAT

 

[leejor]

You'd need to confirm that your 3CX FQDN can be resolved from within your network. Otherwise, SIP messages may be sent out, then back in, to your LAN, which may be causing the issues you are having.
https://www.3cx.com/docs/creating-fqdn-split-dns/

 

[stevehensyel]

I think this might be it as I cannot find our local 3CX sever or IP listed anywhere in the forward lookup zones.

 

[Thabo Maepa]

Hello, I have a similar issue with the Android app. it just says "Connecting" I have allowed all required ports. With no luck still.
It works on the desktop app but not mobile. Works on Mobile data and other networks but not corporate wifi.

Would could be the issue?


We do not use any VPNs, The firewall Test has a few fails as follows: The rest of the ports passed beside the BELOW

• resolving 'sip-alg-detector.3cx.com'... done
• testing 3CX PhoneSystem 01 SIP Server... failed (How to resolve?)
  • stopping service... done
  • detecting SIP ALG... not detected
  • testing port 5060... Mapping does not match 5060. Mapping is 9118. (How to resolve?)
  • starting service... done
• testing 3CX PhoneSystem Media Server... failed (How to resolve?)
  • stopping service... done
  • testing port 5090... done
  • testing ports [9000..9398]... failed (How to resolve?)
    • .......
    • testing port 9118... Mapping does not match 9118. Mapping is 9119. (How to resolve?)

 

[N_G]

If its not connecting then this means that your firewall is blocking traffic to and from the server. App only uses tunnel on port 5090 on the server, rest is for SIP trunks and other server related things. if that is open (TCP & UDP) then the problem on your network is deeper and traffic is somehow being filtered or blocked.

 

[Thabo Maepa]

Good day,

After weeks of tests. i noticed that the network traffic leaves our premises as intended, but it gets dropped by the VoIP server instead of being received. is there something i can check on the 3cx side?

Regards

 

[SyncWave]

Your issue is probably corporate firewall related. Outbound filters maybe blocking somewhat obscure parts like 5090.

 

[leejor]

If you had not yet come across this, it may help in dealing with firewall issues....
https://www.3cx.com/docs/firewall-checker/