Have a client currently using AT&T voice bundled with their data. Since its all coming from their gateway, im assuming its some VOIP plan. Is there a way to get SIP settings and setup a trunk without using a FXO? They’re just a 2 line office with cheap pots phones.
It depends entirely on how they are delivering the data. Without more information about what the modem/router, there’s no likely way we’ll be able to help you.
Note that the most likely answer is “even if there was, AT&T is not going to help you do that.”