Loud and distorted audio on Sangoma S500

I’m working with a company to replace all their desk phones and we are trying out some S500’s but the volume on the handset is really loud and even distorted. This occurs on the DTMF feedback, dialing and remote audio. Even with the volume adjust set all the way down to the 1, the lowest it will go, the volume is still too loud to be comfortable. The web GUI has a volume amplification section and a handset send volume but even with that set to -6, the issue persist.

Model S500
DSP 9.0.3

Attached to PBX Firmware:

PBX Service Pack:

We had this issue with this phone and we narrowed it to G722. Try changing your FreePBX SIP codec order with G711 at top. This fixed it for two installations with S500s having the same issue with “sending” audio being shouty and distorted. Have since moved to Yealinks and never looked back.


It’s the firmware. Revert your phones to the 1.58 firmware package in endpoint manager. This should correlate to the .72 IMG.

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Thank you Brian – I’ve been plagued by audio problems, especially on the headset connected to my Sangoma S700. Reverting to solved the problem. (.73 and .74 both cause nasty distortion).

Client with S705s was having the over-loud handset receive volume issue. Rolling back to 1.58 resolved it for them. Not sure what’s going on with 1.59 and 1.60, but something is certainly amiss.

Just tried upgrading a client and had the same issue. Moved back to 1.58 / fixed it.

Just bumping this as it seems this is still an issue in the 1.62 release as well.

I also had issues and reverted to 1.58 months ago for both S500 and S705. In addition to the same problems encountered, I lost sidetone on all endpoints on firmware above 1.58.

As I did not see anyone else having the problems I presumed it was my system, so it went on a back burner for later investigation.

I’ll add to this as well, but this effects S300, S400, and S705s as well. The additional issue I had was with the S300s. I have some that are on an older cable and force them to 10 Mb for speed. With the latest update, they will no longer connect, they port will just bounce. If I downgrade to 1.58, then they work fine.

So for me, I have the auto negotiate speed below 100 doesn’t work and the sound is pretty bad.

Again, not a pressing project, but I’ll need to open a ticket to have this resolved.


IMO a major bug has been introduced that must be fixed. An important feature of IP desk phones is that they can use existing in-wall wiring originally intended for analog phones, simply by replacing the RJ11 wall jacks with RJ45. Of course, the old Cat-3 or Cat-nothing cable won’t support 100 Mbps, so the ability to handle 10 BaseT is essential. In my experience, Yealink, Grandstream and HTek phones all do fine. Sangoma should stay competitive in this regard.

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Does anyone know if this was fixed in any of the newer firmware versions?


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Having same problem on s505’s and s206’s. Firmware 1.65. Amplification setting on -6db

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