I've been beating my head on a wall on this one and wanted to see if anyone else has had the same issue. I've contacted Sangoma, but haven't gotten very far. My issue is that I'm getting a noise that I could only describe as a hissing and popping on FXS ports. FXO ports have zero background noise. Here are a few other things:

  • I've tried multiple A400s - purchased at different times and probably from different manufacturing runs.
  • I've tried different FXS modules.
  • I've tried different servers (from our standard white box to a Dell PE 2950).
  • I've tested the port on the backplane by dropping an FXO module in - the port is fine.
  • Sometimes, only 1 of the 2 channels on the card is noisy
  • Only unloading wanpipe will make the sound go away (I assume it removes battery from the line also)
  • It's not environmental since I've tried this in multiple environments. I've even taken the stock cable and connected it to a butt set - and STILL get noise


HELP!