One downside of mobile phones is that whoever calls you may be unaware of your current circumstances and the people who are within earshot of your conversation.
This is less than good if, for example, you are being phoned to arrange an interview when your present boss is in the room.
There is probably a privacy-invading solution which invoves carriers pooling location data for any bystanders, but they would have to have their phones on -besides which, the sharing of that information might be illegal.
Today’s invention is therefore a way to alert a caller to the fact that you aren’t free to chat -without the embarrassment of having to say so.
A combination of cellphone button presses could be made to send a tone, or even an ovelaid text message on screen.
A small repertoire of these codes could stand for ‘can’t talk now’, ‘can’t discuss that’, I’ll call you back later’, ‘I’m entering a tunnel’, etc.
These actions could be arranged to be done discreetly by thumb, without removing the device from one’s ear.