Cell phones just use a few different bands that are spread across the same spectrum as all the other allocations, and at lower power levels than a lot of them since it’s running off a little phone battery. There’s no magic frequency that does damage like that - they only get absorbed as heat for the most part, unless maybe you have a very strong signal that’s the right frequency to turn a metal implant into an antenna, or interfere with a pacemaker. Someone with nothing in their body doesn’t have that possibility, so it’s just an inconsequential amount of heat until you go all the way up the spectrum to ultraviolet where you finally have something that’s capable of causing skin cancer.