FYI:
There is a VOIP service allowing individuals to make free voice over ip calls worldwide. That id showed up on my cell phone too. Ask your friends if they are calling you using an internet phone!
Hope this helps,
Mark
[TELECOM Digest Editor's Note: I've had some interesting phone calls lately where the caller ID was given as 'Unknown 119' and 'Unknown 103'. They were overseas calls from Nigeria looking for Lisa when she was not here one day. Playing along with them, I found out they were doing the Nigerian scam. They may have not been in Nigeria, but they certainly did not speak English as I know it. The calls came in on my Vonage VOIP line (which terminates on the PBX but goes through caller ID first.) PAT]