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I’m afraid there isn’t anything that can be done in the ATLAS to modify a call that originates as VoIP. The ATLAS doesn’t support VoIP at all, so the call must be going through a media converter/gateway before being passed to the PRI feeding the ATLAS.
I suggest you have the VoIP service verified to ensure it is provisioned to support modem/fax traffic. It may need to be provisioned for “modem pass-though" - it has to use the g711 u-law codec and pass the tones inband.
Hope this helps,
Thanks. I was hoping there was a trick to reduce echo, etc., or just clean it up somehow. Since the source can be any VoIP provider anywhere, I can't do anything about how it's provisioned.