Within the security world, caller ID is widely known to be broken. Its use as an authenticator SHOULD be none, as it’s trivially easy to spoof the information. Whether you’re using it to call your friends (and make it appear as their boss’ phone), or you’re using it to call the police, making them believe there’s a hostage situation at someone’s home, people place way too much faith in caller ID.

While not the first such service, 123Spoof looks to be making it the easiest to use, for Blackberry users anyway. Their service, an application that integrates with the Blackberry address book, will allow people to call anyone with forged caller ID information, has many international access numbers to use, and even has a voice changer available as an option. While currently free, the only cost to users is listening to a ten second advertisement before their call is connected.

Although most use of this service is likely to be harmless pranks between friends, providers recognize the very real possibility that their services will be used maliciously, and have created an opt-out registry to allow people to block their numbers from receiving spoofed calls.