Good point.  There could be monitoring nodes that figure out which node transactions sent using an SMS service get relayed from, and from there, a number of things could be done to learn of the SMS messages sent at that time and from there identify the sender of a specific bitcoin transaction.



cryptocoin

(you would have to build software to do this, there's no way people would do it by hand) if you *really* wanted to, you could build key exchange over SMS to negotiate a shared symmetric key and then encrypt the transaction. I don't think anyone would *ever* do this, but you could!

rijndael

SMS message size is too small to support encryption 

DeezSats

bitcoin

Bitcoin transaction over SMS?

Keep in mind sending transactions over SMS is not private.