[masraum]

When you "upgrade" from an old phone to a new phone, hang on to the old phone, and keep it charged. Every new phone I've ever bought came with a new sim even if I was going to reuse an old sim, so hang on to whichever is "extra" and keep that around as a backup.

Back up new phone to "the cloud" (or your PC) so you can restore to the old phone. Of course, that only works if the old phone will support the same OS as the new phone. If it was something like an Apple, you could get one of the factory refurb cheaper phones "iPhone SR" or something like that. I'm sure the other major manu's have something similar.