Cannot call from deskphone to 3CX cell phone app

[RDWild]

We have a number of Fanvil X5U deskphones. When an internal user dials the extension of another internal user, and they pick up their deskphone, everything is fine. If they answer with the 3CX app on their cell phone, they cannot hear each other. This is a new installation, we have not had this working correctly, and I do not understand why.

 

[SteveITS]

Does the firewall tester pass? The devices use different ports.

 

[RDWild]

Correct me if I'm wrong, but aren't all those requirements for an on-premises system? Ours is hosted, and all outbound traffic is allowed from our internal network.

 

[SteveITS]

Ah my bad, I view posts from the "new posts" list so sometimes miss the category, and the setup wasn't detailed in the OP. So yes in that case 3CX would control the firewall and nothing to do there. The firewall tester exists, but of course should pass. (otherwise, sometimes people open some ports and not others, which can cause this)

Do you see the same issue with the audio when using cellular data, or other networks, as opposed to company Wi-Fi?

 

[RDWild]

So, this behavior exists on the company wifi, and if we walk outside the range of the company wifi, on the local LTE network, the problematic behavior exists. However we just tried to an extension on 4G in another town, and the calls work fine.

 

[SteveITS]

Well that doesn't seem to make sense. Is the local LTE carrier the same company as the office ISP?

 

[RDWild]

No the local ISP for the office is Cirrinity, the local LTE carrier is Cellcom. The extension we called that was on 4G was verizon.

 

[RDWild]

To add more confusion, we tried a verizon iphone, on the local LTE tower, and it also fails. Calling to cellular users though, not with the 3CX app, works fine.

 

[RDWild]

I got bad information on this issue, please disregard. Will be starting a new post with relevant info.