Both Verizon and ATT offer FIOS. The phone service will function with either service with only a minor setup time.
First, leave the Grandstream powered off. Then connect the ethernet cable provided with the device to a numbered port on the modem/router you have there. The other end of the cable connects to the WAN port of the Grandstream. Once you have the cable connected, power on the Grandstream.
Connect a standard touch tone telephone to the Phone Port 1 of the Grandstream.
Look at the modem you have there. Once you have the name brand and model number of the modem you received from the ISP, refer to the Customer Provided Routers category for information on how to configure your modem to function with our service.
If you are unable to place a call after completing the above instructions, please contact our support department for additional assistance.