Now this is something very, very useful...

This update from Larry Seltzer at PC Magazine got my attention:

"There are few things as annoying about cell phones as getting calls with blocked or restricted caller ID. You don't know who it is, but you're going to have to pay for the call. That's not right, and it's why TrapCall is so useful.

TrapCall only works with mobiles. First you program your phone appropriately with a simple sequence. Then, if a call comes in without caller ID information you press the key on the phone that sends the call to voice mail. On my BlackBerry it's the "Ignore" button. TrapCall then secretly routes the call through a toll free number of theirs so that they can examine it. A few seconds later the call rings back at your phone with the caller ID information.

Well, most of the time. Tests of classically blocked caller ID (for instance by using *67) work great through TrapCall. But where there is no caller ID information on the call at all, i.e. where caller ID shows you "Unknown Caller", there's nothing they can do. TrapCall returns with a number of 9999999999. TrapCall says this is common with international calls and some VOIP PBXs.

For just these coolest capabilities TrapCall has a free service called FlyTrap. FlyTrap also allows you to blacklist unwanted callers and provides web-based voicemail. For-pay subscriptions add features, including toll free support, recordings of your phone calls, even transcriptions of your phone calls. I tested the recording service and it works, although for legal reasons people you talk to will get a warning that their call is to be recorded. It can be a bit off-putting, but in my line of work I interview people and it could be handy to have a recording like this; You can turn off the warning at your own legal peril.

The blacklisting service is just too cool. You enter a number or select a caller in the call log in the web console to blacklist them. Then if they call and you press the send-to-voicemail button on your phone the caller hears "Sorry, the number you have dialed has been disconnected or is no longer in service."

Read the rest of Larry's observations at http://tech.yahoo.com/news/zd/20090323/tc_zd/238420