A colleague is trying to call you while you’re in a meeting. You can’t answer the call, and need a way to signal your availability besides just dumping the caller in voice mail.
With a trivial modification, you can use your phone to send a canned SMS message back to the caller. This requires a change to the phone’s software, but will be easy to do. In some cases, such as Palm and PocketPC devices, you might be able to do this hack yourself. In others, you’ll need to wait for the device manufacturer to implement this. In either case, it is a very simple trick, and so there is no reason not to do it.
I have a Treo 600 smartphone. When I receive an incoming call, the phone displays the incoming call information, along with two prominent softkeys, one labeled Answer, and one labeled Ignore. This display would be modified to display three buttons, with a third one labeled Ignore w/ Message.
When I push Ignore w/ Message, the phone diverts the call to voice mail, and then displays a menu with several large buttons, each corresponding to a canned SMS/text message (e.g. “I am in a meeting now, I saw you just called, and will call back in a while.”). You push the desired button, and then the phone goes off and tries to send an SMS message back to the calling party. The caller will receive the text message, and will then know your status.
This system will work well for mobile-to-mobile calls, but will not work for land lines, since no SMS capacity exists for most landlines. However this should work quite well for calls from other mobile phones. It’s a simple enough trick to implement, so especially for smartphones, this would make a lot of sense.