[seiji]

Depends on what you mean by "spoof."

Anybody can generate custom outgoing caller ID numbers. That's not really a "spoof," that's just lying about who you are when you make a call.

Most phone "spoofing" would be if someone cloned your phone number and the phone was registered multiple times on the same network, so when you got a call, one or more of the phones would ring at the same time.