Solved No AUDIO call with Yealink T21P E2 (3CX v16)

[rachmadona]

hello team,

i have 3cx version 16.0.504 installed on top Windows Server 2012 machine and IP phone yealink T21P E2 provisioned with STUN (firmware 52.84.0.95). Somehow i have two problems:

1. Whenever either i got incoming call from external or make outgoing call to external with IP phone i could not hear anything once the call is picked up
2. But if i tried to call within internal:
   1. IP phone to IP phone doesn't work
   2. IP phone to Windows/web client sometimes works, sometimes not. Need to drop the first call, then wait for couple minutes, making call again and it will work.

i can ensure firewall check has passed and all codec is similar. any advice would be very appreciated.

regards

 

[cobaltit]

Some topology information would help. Is 3CX and the phone on the same network? If so, you shouldn't be using STUN.

 

[rachmadona]

Thanks for the prompt response @cobaltit

My 3cx located on cloud. I am using VPS.

Simple topology:

IP phone/windows/web client----unmanaged switch---router---internet---3cx vps

 

[cobaltit]

I wasn't sure since you said it was running on WIndows 2012 (speaking of which, with Update 5 you need to be on Windows 10 or Server 2016+).

Firewall checker passing is good but that's only half the equation. You'd want to make sure you forward the SIP and RTP ports listed on the phone provisioning tab to the IP phone. You'd also want to make sure SIP ALG on the router in front of the IP phone is turned off. The other option is to setup a SBC and then you don't have to worry about any of that. Slightly overkill for a single IP phone but if you envision having more than one at some point it's well worth it.

 

[rachmadona]

may i know which update should i use if i am on Windows Server 2012? as VPS provider unfortunately can offer such. Also i confirmed SIL ALG is disabled.

That would be a good option for SBC. Let me test internally and get back to you with the result.

 

[cobaltit]

https://www.3cx.com/blog/releases/apple-push-update-windows/

 

[JohnS_3CX]

Hi @rachmadona

The next update will make it necessary to move to a newer Windows Server ( or alternatively, you can deploy our Debian ISO on the VPS) because we will no longer be supporting or testing the system on Server 2012.
https://www.3cx.com/docs/manual/

On your STUN extension, edit the options and make sure "PBX Delivers Audio is enabled" since we are a remote extension now. Then as @cobaltit said, you need to set port forwarding for the SIP+RTP ports the phones uses in the firewall its sitting behind. If you will add more phones, SBC is an excellent option as it eliminates the need for special settings and port management.

 

[rachmadona]

Thanks All.

The issue seems resolved once i upgraded to Windows Server 2016