You can't send a phishing SMS from a receive-only device. Any mobile tower must have an active transmitter (at the very least, so the handset knows what network

You can't send a phishing SMS from a receive-only device. Any mobile tower must have an active transmitter (at the very least, so the handset knows what network it thinks it's connected to!). Transmitting on a licensed mobile service band without the license is a very good way to earn a knock on your door. Eavesdropping on tower-to-handset comms is illegal too (in the UK), but it's not very practical to find just a receiver, unless they already know almost exactly where it is and are able to do a TEMPEST-like attack on the local oscillator or something. So as long as you keep quiet and don't do anything to indicate you're listening, such as, posting on Twitter about it or you do crime based on it, you'll get away with it. However, a receiver can't bump a victim handset down to a primitive-enough protocol, so all you'll get is encrypted content and maybe a smidge of metadata (I'm not sure exactly what is and isn't encrypted for each "G").