Cannot call from 3CX phone to cell phone

[RDWild]

I have a situation where if someone calls from a 3CX phone, to a cell phone number, the phone rings, the user answers, but neither end can hear anything. Calls from the cell phone to the 3CX phone are fine. Cell phones with the 3CX app are fine.
We have tested with different carriers, and in range of different cell towers.

 

[RDWild]

 

[TheodorosG_3CX]

Can you please try and manually update one of the devices and check if the issue is still there?

 

[RDWild]

How do I manually update? There does not apear to be an option to do that. If I go to the phone URL, System -> Upgrade, and upload the file there, it does not upgrade the phone, it remains at 2.12.1

 

[TheodorosG_3CX]

You may check guideline of how to proceed:
https://www.3cx.com/sip-phones/firmware-update-fanvil/

 

[RDWild]

That is what I have tried. Upon selecting upgrade, eventually I get "The connection was reset", then after a refresh, it is still 2.12.1

 

[RDWild]

Problem continues. Turned off "PBX delivers audio" - seemingly no difference. Changed SBC to use a router phone vs a SBC installed on a windows server - seemingly no difference.

 

[Alphabetic]

btw, license still showing as attachment.

 

[RDWild]

I can no longer edit that post.

 

[RDWild]

Still an issue. Can't go production with it like this.

 

[RDWild]

So, more information on this.... This environment is a mix of one Yealink T57W and 18 Fanvil X5U phones. The Yealink T57W phone works fine. The Fanvil X5Us are the ones with the issue. In fact, if a call is placed on the T57W and then transferred to the X5U, the phone call works fine. Only when it is initiated by the X5U is there an issue.
We have a software SBC installed on a Windows 2022 server, the T57W is also a router phone. Tried running the Fanvil through the dedicated software SBC and the T57W, no difference.

 

[leejor]

if someone calls from a 3CX phone, to a cell phone number, the phone rings, the user answers, but neither end can hear anything.

So...do calls to a landline number (any number) have the same issue, or just calls to, what you know, is a mobile?

 

[SteveITS]

if a call is placed on the T57W and then transferred to the X5U, the phone call works fine. Only when it is initiated by the X5U is there an issue

Are both phones set to use the same codec that the SIP trunk is using? It's not that a codec is missing? (vague brainstorming...)

 

[RDWild]

So yeah, the Fanvils are set to defaults (PCMU, PCMA, G722, and G729). Where exactly do you set the codecs on the SIP trunk?

 

[SteveITS]

So yeah, the Fanvils are set to defaults (PCMU, PCMA, G722, and G729). Where exactly do you set the codecs on the SIP trunk?

open trunk > Options > Codec Priority (bottom of page). If there is overlap it should "just work" but I was taught to keep the same order, and prefer what the SIP providers uses, so there is no transcoding.

 

[RDWild]

It shows G.711 U-law , G.711 A-law, and G729. Again, must be defaults... I have other clients that are set up the same.

 

[SteveITS]

PCMU=G.711 U-law
PCMA=G.711 A-law

There are defaults but SIP provider templates will set that for you on the trunk. (there is also a setting for codecs in Settings/Apps, though not relevant here with phones).

Feels like "Only when it is initiated by the X5U is there an issue" is an important clue.

 

[RDWild]

Right? I agree. I have other clients with Fanvil phones without issues, however, in this instance, they are using X5U version 2.0, which is a model I have not used elsewhere.

 

[TheodorosG_3CX]

You mentioned though that the issue is only when calling mobile numbers correct?
So for normal local phone numbers there is no issue?

 

[RDWild]

I need to do further testing to absolutely confirm that, but yes. Calling other land lines is fine. Calling 3CX extensions that are picked up on a cell phone are fine. Only calling cell numbers seems to be a problem. I have Fanvil involved, and tomorrow we will be doing some network captures for them.

 

[TheodorosG_3CX]

This is weird though and i believe it is also related with your provider.