Sangoma s300 audio issue

Hey guys,

I’ll admit I’m fairly new to FreePBX, and VoIP Phones in general…
But I bought a pair of Sangoma S300’s because I had heard they were easy to get going, and I figured that I’d start with some easy phones and make my way up.

I’ve setup several phones, including a few sophphones, but I wanted some hardware phones for my shop, mostly for the presentation, and easy of access to dial my techs in other parts of my office

So here’s the problem: I’ve got 2 Sangoma S300’s setup with FreePBX, they registered just fine and all that. I can dial other extensions perfectly fine, and other extensions can dial them. However if the phones connect to eachother something weird happens. One phones both transmits and receives voice just fine, but the other one just sends data.

I’ve ruled out faulty hardware, swapped cables, handsets, everything. Just to be clear, the phones operate perfectly fine, except when dialing eachother… which is one of the main reasons I got these phones.

I hope some of you may be able to help me.


Not sure what you’re describing here. You say one phone works but the other only sends data…can you tell me what you mean by that? If the second phone only sends, then how do you know that the first phone transmits just fine?

Its the strangest thing, but I’ll do my best.

So the phones work 100% fine in every use scenario, except when I use one to dial the other’s extension…

On phone #1, it sends, and receives voice just fine. I know it sends because I can hear it on the phone itself, like an echo.
On phone #2, it sends voice fine, because I can hear it on phone #1, but no matter what I do on phone #1, I cant hear anything in the call on phone #2.

I don’t know if its normal to be able to hear yourself in a call in the background, (new to VoIP Phones) however if it is not, then it’s almost like the voice data from #1 is just looping back to phone #1, because it can’t reach phone #2

I hope this clear this up, or maybe i made it more confusing lol. Either way let me know what other information I can provide that would help


This truly sounds like a network issue to me. Are both phones on the same network as the PBX or are they natted?

Yes, they are on the same local network

The only reason I don’t think it’s a network issue, is because I can use several different softphones to call both of the Sangoma S300’s (again, same network) and they both send a receive voice just fine

This almost sounds like a port/session conflict…what kind of firewall/router do you have? Is your network switch operating on layer 2 or layer 3?

Can you confirm the IP address, netmask, and gateway of each phone for me? Are they configured with static IPs or a DHCP lease?

I have 9 s300s deployed in a small office and they have zero issues with calling between phones.

So the issue has been resolved.

I restarted he server after updating some modules, aswell as I created brand new extensions for them and factory reset the phones before assigning the new extensions

One of those things, or a combination of them all resolved my issue

Thank you for your help guys, sorry for being a bother lol

Have a nice day,