Mobile phone deception

The Economist talks about how mobile phones are used for deception.

SounderCover allows certain Nokia handsets to play pre-recorded bursts of traffic noise, airport announcements or other sounds in the background during a conversation.

Two services offered by American operators, Cingular’s Escape-A-Date and Virgin Mobile’s Rescue Ring, allow customers to prearrange a call at a given time, to enable them to get out of a disastrous dinner date or boring meeting.

I would personally like a service that says “This phone is unreachable” instead of an engaged sound, when I cut the call off.