How to Hook Up a Fax to Comcast Phone Lines

By Maya Austen

Comcast’s Xfinity voice service does not use traditional phone lines as it is delivered via fiber optic cable Voice over Internet Protocol (VoIP) technology. Xfinity voice customers can use regular fax machines with their Comcast phone service. Instead of connecting the fax machine to a telephone wall jack, as is the case with landline phone service, the fax machine is hooked up to the Comcast eMTA or gateway device.

Things You'll Need

  • Comcast eMTA or gateway
  • 75 Ohm coaxial cable
  • 1 or 2 Telephone cables

Step 1

Connect one end of the coaxial cable to the cable wall outlet put in by the Comcast technician. Connect the other end of this cable to the RF “Cable” input terminal on the back of the Comcast eMTA or gateway device.

Step 2

Plug one end of a telephone cable into the second telephone jack on the back of the Comcast eMTA or gateway device. Plug the other end of the cable into the telephone jack on the fax machine labeled “To Wall.”

Step 3

Use the remaining telephone cable to connect the phone jack on the fax machine labeled “To Phone” to the phone jack on the base of the telephone. This step is optional, the fax machine will work even if you don't connect it to a telephone.

Step 4

Connect the power cord that came with the Comcast eMTA or gateway device to the power jack on the back of the device. Plug the other end of this cord into an electrical outlet. Plug the fax machine’s power cord into an electrical outlet.

Tips & Warnings

  • The Hitachi Omni Fax HF18TME is incompatible with Comcast’s Xfinity voice service.