What phone models are involved? I couldn't find the info, sorry if I missed it.

It's not hard to emulate a SMS, but I think you are making a mistake in assuming a person's ability is beyond it. In many countries, I'm assuming yours too, there are people that have high knowledge of phone's inneards and do several ... services for a few bucks. Such as flashing, unlocking, etc. Such a person and 5$ could make anything appear. I've seen these guys unlock phones launched yesterday.

What you can't really fool is the phone company. Well, you can, but you need gateway access and that's way harder. Way.

Phone models also count, because a lot of phones are susceptible to infection. Most symbians are. As a result, a slightly modified virus could be sent by accepting a BT link (easily done if you get a hold of the device for even a couple of seconds). Such a virus could be used to send anything to anybody, complete with phone company records. If this the case, good luck with that.

It might sound like science fiction, but remember, the unlocker guy a few blocks from you will do this for a few bucks. Heck, I think I can if I really want to. Old viruses are now open and some use txt files to read number and message.

Oh, also, on a lot of models, Nokia PC suite doesn't restore SMS'. This could exclude that. Still, I believe it to be the easiest way by far. Just fiddle with an editor in the backup and wait for the idea to strike.