I have an HP M1217nfwMFP all-in-one printer, fax, scan, copy. We just had ATT U-Verse installed in our home. The phone co used the wall outlet. I don't have an outlet to plug fax into wall jack. Do I have to have the fax plugged into a wall jack over the wireless router?
No, the router is for digital data, and your fax machine is analog and must be connected directly to a phone socket. You can buy a "phone socket doubler" which will give you an extra phone socket for your fax machine. The socket doubler is the phone-socket equivalent of a mains adapter plug which converts one mains socket into two or three sockets.