Muffled sound in audio conferences

[ls3]

Hi, we have very muffled sound if we make audio conferences with phones.

Phone 1 calls phone 2 -> crystal clear
Phone 1 calls phone 3 -> crystal clear
Phone 1 makes the conference and than the sound is directly very muffled for all participants.

This also happens on "normal" audio conferences or if someone dials in a webconference with a phone.

Is this normal behavior?

1:1 connections are always crystal clear : - /

 

[Aaron Paul]

Are you noticing any bandwidth issues during the conference calls?

 

[cobaltit]

You said phone 1 makes the conference call but you didn't mention where the participants are or how they joined. If the first two examples are internal only extensions and the third is external then it's likely a transcoding issue. If the first two are internal and the third is internal calling the conference DID (which makes it external) then it is also likely a transcoding issue. If you've changed any codec settings for the extensions but left the 3CX defaults it could be a transcoding issue if the conference bridge is calling the users. You also didn't mention what phone 1/2/3 is (IP phone, Android client, web client, etc).