Yealink T21P E2 | Voice Not Working

[inexame]

Hello,
I have a problem with calls, because when I communicate with the phones in the office, there's no problem, everything works fine, but when I try to communicate with other offices that has 3cx installed, they receive my call but there's no audio. In my company we have 3 offices, and the problem is just with my office, the other two can communicate without problems. Also, if I use the 3cx Windows App, everything works perfectly, it's just when using the Yealink Phone.

Could somebody help with this problem?

 

[JohnS_3CX]

Sounds like you have some routing issues. Are you the admin of the PBX?

 

[inexame]

Sounds like you have some routing issues. Are you the admin of the PBX?

Yes, I'm the admin.

 

[JohnS_3CX]

Ok start from here please and we will see how we can help:
https://www.3cx.com/community/threads/post-in-relevant-category.115838/

Plus: We need to know more details about the other sites too, how they connect to the main site

 

[inexame]

• 3CX Version,18.0 (Build 418)
• Server OS, Google Cloud Marketplace Default Install
• Is the 3CX Server Hosted and where? Google
• IP Phone Make/Model/Firmware version, Yealink T21p E2 version T21P_E2-52.84.0.140
• Provisioning Method: Local
• Trunk Provider or VoIP Gateway Make/Model, DIDWW
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: NO

Site 1: Connected to the internet all phones are Siemens OpenStage 15 (using direct SIP), which works fine inbound, outbound and internal calls through an SDWAN connection, calls to and from Site 2 work perfectly.
Site 2: Connected to the internet all phones are Siemens OpenStage 15 (using direct SIP), which works fine inbound, outbound, and internal calls through an SDWAN connection, calls to and from Site 1 work perfectly.
Site 3: Connected to the internet, phones are Siemens OpenStage 15 (using direct SIP) and Yealink T21p E2, which work fine for internal calls through an ISP connection, calls to and from Site 1 and 2 work without sound (voice). Strangely 3CX windows app installed on a pc on the same network with the same Internet Access can receive and send calls to sites 1 and 2. Also, both phones (Siemens and Yealink) can make and receive calls from a smartphone using the 3CX app. We have tested both phones on another branch with normal internet access and they can both send and receive calls from sites 1 and 2. It is just this branch that cannot communicate with sites 1 and 2.

 

[JohnS_3CX]

Site 3: Connected to the internet, phones are Siemens OpenStage 15 (using direct SIP) and Yealink T21p E2, which work fine for internal calls through an ISP connection

When they call between themselves at site 3 they are fine, because RTP can travel freely on the same LAN

calls to and from Site 1 and 2 work without sound (voice)

RTP packets cannot travel from site 3 to site 1 or 2 - you have to fix this part most likely

Strangely 3CX windows app installed on a pc on the same network with the same Internet Access can receive and send calls to sites 1 and 2.

That's not comparable - the app uses a tunnel connection to reach the PBX and is not affected by your SD-WAN routing or SIP-ALG

Also, both phones (Siemens and Yealink) can make and receive calls from a smartphone using the 3CX app.

RTP packets can travel between site 3 and the cloud PBX. External calls should also work fine (ie. when using SIP Trunks).


Try to enable "PBX Delivers Audio" on all the extensions at Site 3, and you should now have audio when you call sites 1 or 2. If this works as I predicted, then you have evidence about what I said you should fix above. This basically forces the audio to travel via the PBX, acting as an audio proxy and bypassing whatever rules Site 3 has that prevent it from routing RTP back to site 1 and 2.

You could leave it that way, but you are unnecessarily forcing all (even local) traffic from site 3 to always go via the PBX and back.