Hi! I didnt know for sure but the other day I got my order in from cayces cures.-- I ended up buying a diode for my Cell Phone -- it says on the package that it is now also good for analog and digital phones too.
What I noticed after attaching it on my phone is that I don't get a high pitched sound coming from my phone now and can actually use the Cell Phone up to my ear without my usual hands free head set.
Maybe I am really sensitive to these things, but using the cellphone without any protection whatsoever always had a high pitched wierd tone to it in my ear that gave me a headache. Noone else noticed it. The diode stopped it. I am still going to use the head piece as well.