Hi Joel,
I posted the answer here from a product engineer, because it is very relevant to other folks who probably have the same question.
There should be no problem ringing a phone(<=1 REN) with 1200 feet 24AWG wire.
UC320W has higher ringing voltage(53Vrms vs. 40Vrms) and it should ring a phone from longer distance.
However we don't recommend this kind of off premise usage as the FXS port, as the FXS port is designed for on premise use.
The protection circuit may not be strong enough to survive the high voltage introduced by lightening, if the cable is run between building and not in metal conduit.
If the cable goes outside the building, it could very well be susceptible to lightening and other induced interference.
regards Dave