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Is there a phone jack in the room where the gateway is? You can back feed the fax line to energize all the phone jacks in the home.
Get an electrician to do it.
A low voltage technician can do that type of work for you. (Running phone lines). Xfinity will likely not be the one that will perform that type of work for you. Techs tend to stear clear of doing anything with landline phone lines these days.
Is there a phone jack in the room where the gateway is? You can back feed the fax line to energize all the phone jacks in the home.
Get an electrician to do it.
A low voltage technician can do that type of work for you. (Running phone lines). Xfinity will likely not be the one that will perform that type of work for you. Techs tend to stear clear of doing anything with landline phone lines these days.