can I block a number

You are correct, but it is only semantics.

From a user point of view, if I can set a number to be blacklisted and get the result where when that number calls, my phone does not ring, vibrate, show any other indicatation that the number called, then it is blocked.

At the point I don't care if it was blocked by the carrier or the phone, or if it called blocking the call, hiding the call or making butterscotch out of the call.

And no, they can't leave a voice mail if you set it up pickup/hang up. And even if I sent it to voice mail, who cares. I can see who it is when I look at my Google Voice inbox or "Visual Voicemail" and a swipe of the finger deletes it without me having to hear it.

Rick Cross wrote:

I can see who it is when I look at my Google Voice inbox...

If you are using Google Voice, why is this even an issue. You can blacklist them on the Google Voice web site.

Because, my iPhone has its own number that gets annoying calls too.

You could report them as spam by sending a text to 7726.

Give us a hint on the iphone app that works.

maybe e a code with every 3rd letter spelling the name

There is none that works. It's not possible. The APIs necessary to do this are not public.

This seems like an important feature that many people would find valuable. Any chance of this being available in the iPhone 5?

"Some carriers, including AT&T, offer call blocking for a free."

AT&T does not do anything for free, not even block a number for you but they do have a monthly plan for $4.99 that will do just that for up to 30 numbers called "Smart Limits".

"...download a "Silent" ringtone (Just search on google for silent iPhone ringtone and you will find plenty of them), create a contact entry for the number you want to ignore, assign the silent ringtone to the entry and your phone won't ring when they call. You may need to turn off vibrate when called in settings if you want to completly ignor this caller."

This does prevent you from hearing the call ring and yes you can stop it from vibrating as well, however it now goes to voice mail without you knowing about it and then you get a message letting you know you have a voice mail instead of getting a ring which is just as annoying.

"This seems like an important feature that many people would find valuable. Any chance of this being available in the iPhone 5?"

Nope not on the iPhone 5 either.

I'm sure that was a typo; Tim meant for a "fee".

But the fact is that it is technologically impossible to block a call once it reaches your phone (any phone, not just an iPhone). Because it has already reached the phone. So the best you can do is ignore it. which means that it will go to voicemail. Blocking apps that are available on some phones don't really block the call, they ignore it. So the calls will still go to voicemail.

If you want true call blocking and you don't want to pay AT&T $5 a month for the privilege get a VOIP number and give it out as your mobile number, then set it to forward to your mobile. Google Voice has blocking, and it's free for incoming calls.