Sangoma A101/Adit600 Noise

I have a new installation in a Dell using a Sangoma A101 and an Adit 600. The Adit has 2 FXS cards and one FXO. When a call comes in, about 50 percent of the time, the caller hears noise like a modem. After a while, maybe 2 rings, Asterisk picks up the call. The noise may persist during the call. Other times it works great and picks up the call right away with no noise. I have verbosity turned up and see no odd indications.

I have software signalling set up for kewlstart and the Adit DIP switches all off on the analog interfaces. (I think that’s loopstart)

Any ideas?

Thanks!

I’m using an A101 with a TA750. The FXO channels are ground start and the FXS are kewl start. No modem sounds here. Works well.

I couldn’t get the FXO channels to hang up when set to anything other than ground start but don’t remember hearing a modem-like screech in any of the configurations I played around with.

As an aside, the FXO lines are horribly susceptible to RF so I have DSL low-pass filters attached to each. Cures it.