Internal Calls Muffled/Dull

[dhart21-3CX]

We have a customer, had the system in for a week and is reporting that all internal calls are muffled and audio is dull. External calls are ok.

Draytek router with SIP ALG turned off.

Rebooted PBX and Handsets. It sounds like a codec issue but would would appreciate it if any one had any insight?

• 3CX Version, Professional Annual 16.0.5.622
• Server OS, Debian 9.5
• Is the 3CX Server Hosted and where? Amazon Ligtsail
• IP Phone Make/Model/Firmware Yealin T46S F/W 66.85.0.5
• Provisioning Method: Local STUN
• Trunk Provider or Gateway Make/Model Voiceflex
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: NO

 

[Alphabetic]

Have you checked "PBX delivers audio" on all STUN extensions?

How many handsets are we talking?

You may have to give the phones static IPs and port forward unique SIP and RTP Ports per phone.

Each Yealink will use 12 RTP ports.

Example:

EXT 101 SIP PORT 5060 RTP 14000-14012
EXT 202 SIP PORT 5061 RTP 14013-14025

Specify this under phone EXT and re-provision them. You'll need to ensure the phones have static IPs too.

You may want to consider an SBC to mitigate having to do this as traffic will flow through SBC tunnel without the need for static IPs and port forwarding.

 

[dhart21-3CX]

PBX delivers audio is enabled on the SIP trunk and on each extension. I know this as when it was disabled, I was getting no audio on internal calls.

10 handsets, but only ever 4 people at anyone time in the office due to COVID-19.

Does 3CX support HD calling? Could it be a codec issue with 3CX and voiceflex

 

[Alphabetic]

Voiceflex support G.711u, G.711a and G.729

I would suggest an SBC to save yourself the hassle. But, you could do what I mentioned above of a few phones and then see that it sorts the problem.

 

[dhart21-3CX]

I am looking into the SBC setting. As I have never done this before, its a bit overwhelming.

 

[Alphabetic]

You needn't worry - it's really simple and well documented.

How are you looking to set up the SBC? On a dedicated Windows machine or using a Raspberry Pi?

Pi's are very inexpensive and can be hidden next to the router.

Does your site have a HyperV server where you could host a virtual machine?

https://www.3cx.com/docs/3cx-tunnel-session-border-controller/

You'd follow these instructions to get the Raspi OS on the Pi right up until it starts mentioning installing the PBX. But, instead you'll follow the first link above to install SBC.

https://www.3cx.com/docs/installing-pbx-raspberry-pi/

 

[dhart21-3CX]

I wasn't looking at setting up an SBC. STUN would have been the way forward for us. Hosted PBX with amazon and away we go.

Adding an extra device/hardware to the list is now adding extra cost on to this and something we don't want to get involved.

We were/are looking for a simple hosted solution thats cost effective.

I may try the SIP port you mentioned earlier. Only issue is that every Yealink has the port 5060 enabled in the GUI and I am unable to log into phone now.

 

[Alphabetic]

If you dont want to use the SBC then these are the type of woes to expect with having multiple STUN devices on the same network.

You wont be able to access the phone GUI using the button from the MGMT console. You will need to get on to the subnet the phones are on and access them that way.

As mentioned earlier you will need to give each phone their own unique ports, re-provision them then give them static IPs and port forward to the 10 phones.

When I set up my first site (6 phones with STUN) I came across the same problem and it was such a ball ache messing around giving static blah blah. I will never again want to do it this way for devices more than a couple using STUN.

There are tales of users using an external SBC but you'd have to do a search on here for that.

 

[dhart21-3CX]

I will one day look at an SBC. I will save this thread for future reference. For now I am going to move my customer to our other hosted supplier which is PnP.

Thank you.