My Idea, If they have just a few bucks, Sell them a Legend R7.0.
That way, they can still use the ANTIQUE phones they have, and even get their own Voice Mail if they so choose.
The advantages are that they will have a system with Remote Programming/Trouble shooting capabilities, plus backup and restore, and a system that has Cheap and Available parts. I could go on and on.....
More than likely the Battery in their current FEATURE PACKAGE is shot, and this will happen each and every time they loose power. With a LEGEND, even if the Processor Battery is shot, you can at least restore it from the PCMCIA Backup Card.. (But most likely, the Legend Processor Battery will last a long, long time)
This recommendation is based on experience. About 12 Years ago I replaced a failing MERLIN II System Processor at a rather well known client's office because of a power problem that wiped out their memory. The owner asked; "If we ever have power go out for 3 or 4 days again like it just did, will I still loose my Programming?" Of course, my answer was "YES SIR, with this MERLIN II you will". His next question was; "What's the cheapest way we can keep this from happening in the future?" The Legend, with it's back up capabilities sold itself right then and there.
He kept that R7 Legend (+ the Voice Mail I sold him) for another 10 or 11 years. It served him quite well.
Just my 2 Cents worth.