For a while now we’ve had the strangest problem with audio on calls going through the Asterisk box. Basically, it’s about repeated audio. Not in a classic “echoing” way, but rather more of a delay that occurs periodically.
Whenever this occurs, the audio of the external party (the party calling in to the Asterisk box) is played, then repeated a fragment of time (like 0.5-2 seconds) later. It might occur midway in a conversation, rarely from the start.
Our setup is purely SIP/IAX based, and the external party has never complained about sound issues, so I take it that this only applies to users on our end.
At first I thought that this might be issues with our provider, so I asked them to supply us with calls from another trunk, which they did. But then I even found that there were similar sound issues when calling in to a MOH-extension(!).
Our setup is 4x CISCO 7960s, SIP-firmware v. 8.2, and the the PBX, which is a Celeron 2.4, 512 MB RAM running Fedora Core 5. The Asterisk box itself is running the 1.2-branch, although I have been frequently updating this through SVN, so it really shouldn’t be related to just one particular 1.2.x build.
I doubt this is related to our internal network, as I have taken the effort replacing both the switch and the router separating the PBX from the rest of our office network without results. For the record, I have two of these Celeron computers laying around, and the issue persists on both machines.
I am getting lost here. I am left with the possible theories that it might be either:
- The OS itself having issues with the hardware (the OS is fairly recent, but we had similar issues with the Centos 4.x branch before installing Fedora last fall)
- An Asterisk-related bug, or
- A bug relating to the Cisco phones.
I wish I could exclude the number three, but to be honest, this problem has been going on for so long I can’t recall if I ever was able to recreate the issue using Xten or other softphones. Since it’s very periodical, it’s really hard to debug using the elimination method.
I should add: If I put the call on hold and then pick it up again, magically, the echo is gone - at least for a while…
Any feedback would be appreciated.