Cable is not telephone. You don't use a cable connection to dial out on.
EXCEPT! (and there are always exceptions, aren't there...) if you have the type of cable service where your cable provider is selling you telephone service on that one line (which might even be an optical line). Sometimes there are packages of mixed services (TV, Internet, and telephone) on that one line. But, if you have that, and are subscribed to it, you will then have a converter box usually somewhere on the outside of the house, that "splits" that one cable into the three types of services and sends that portion down a devoted set of house wires.
In the case of a telephone service, riding on cable, your converter box will have a set of wires from it to the regular telephone house wiring. In that case, just treat the telephone house wiring exactly like any other regular house telephone system.