Take a look at my
Recording Phone Calls page and scroll down to the wireless phone recorder thing. It works for any cellular phone that has the standard headset jack on it.
Another device that I don't have up on that page yet is Radio Shack's
Olympus Mini Tele-Recording Device. I just bought one a month ago and used it for recording the pay phone calls on PLA Radio #12. You put it in your ear and it looks like you're just wearing a normal cell phone earpiece. But it only plugs into your recording device. It doesn't actually plug into the cell phone. It records whatever electronic device that you happen to put up to your ear. It's just like the suction cup induction coil, but it's stuck in your ear instead of to the back of the phone's handset.
The only problem I had with it, though, was that it didn't pick up MY voice very well. So I used it alongside one of those "tie clip" microphones. The combination of the two worked great. It seems to pick up my voice okay on my own home and cell phone, though, so maybe the pay phone I was at just sucked.
