Cell Phones for Soldiers packet with Amazon.com shipment?

[Mr. Hanky]

Anybody get one of these plastic envelopes with their recent Amazon shipment? They ask for you to recycle your old cell and send it in the prepaid mailer.

While it sounds like a good gesture...I thought to myself, how would they make it work on the other end? A cell needs a service plan to function, needs the little smartcard inside it to have an identity, and there has to be functioning towers that host that service, right? What about supported bandwidth compatibilities and domestic vs. foreign telecommunications protocols? So how is that supposed to work on some military base located "in-country"? If it is an older cellphone model, how are they supposed to guess which service can still support that phone?

Is this "Cell Phones for Soldiers" thing legit?