We are using ATA2 adapter as an regular extension. Then send the analog output to a SIP device, which talk to another SIP device over Internet, so the actual phone is
actually 10 miles away, but works as an extension. But before going to SIP device, analog phone connected to the ATA2 adapter can get features and transfer calls by flash*70
With SIP carry the extension to 10 miles away, flash*70 does not work. But talk over the phone people don't know the other person is actually 10 miles away....