iPhone - Tip of the week - Sending a call directly to voice mail

I have been asked several times how to send a call directly to voice mail without waiting for the ringing to end, I am documenting it on my blog.

When a call comes in, the iPhone wakes up, rings and/or vibrates and the caller id information is displayed (blocked, unknown, phone number or associated iPhone contact information).

You have three choices:

1. Answer the call by sliding your finger to answer.
2. Depress the power button once to silence the ring. This just silences the ring, you can still answer the call by sliding your finger. If you do not answer the call within the 25 second default timeout, the call is forwarded to voice mail.
3. Depress the power button twice. This silences the ring and forwards the call directly (no timeout) to voice mail.