While I have no direct experience with those devices, I DO work for a manufacturer of networking equipment, and have dealt with telephone companies quite a bit in the past. So I'll hazard a guess, based on my understanding of their mindset and procedures.
Any particular phonecall may be life-critical, and system failures can leave thousands without phone access - whether cell, landline, or what-have-you. Then they get refunds, and there is a big stink.
So telephone equipment - even the stuff for the new-economy upstarts - is built to higher standards than mil spec. "Five nines reliability" is minimum, and six nines is considered good.
Two inverters and a power transformer from a cell site? You BET they'll be useful for a home power system. I'm drooling at the thought.
Tellcos tend to be big on powering things from 48 volt battery banks - two of 'em for redundancy. Postitive ground (because that way if it gets wet the corrosion happens on the surrounding metal, not the telephone wires.) And their color codes are backward from what you're used to. Red is HOT, i.e. -48. Black is Neutral. Don't fry those puppies. I'm not sure what they use at cell sites, but I'd be really surprised if the DC wasn't -48.
