So, how long until someone figures out that they don't actually need to save someone's life to send a text message? And what about using the blood when someone's life is not saved, does that not warrant a text message? How come the entities using the blood and/or distributing it have access to the phone numbers of the donors?
I imagine it works pretty much as you suggested below: each bag of blood is identified with a serial number, the collection agency is alerted when that bag is used, this triggers a message from them to the donor.
Would you be happy with that?