Blinding Idea for phone menu systems

[Lockhouse]

I always have my mobile on silent. I'll check my phone when I'm ready thank you. Occasionally I might just play my ringtone for the hell of it.

[Lockhouse]

Why can't mobile phone operators agree on a standard short warbling sound, or even better if it is possible an inaudible control signal, to instruct one's mobile that the current call is to a menu system and will require the caller to type input, generally numbers?

That way the phone would know to maximise the number keypad on the display without the user having to press a button to do this. Drives me potty having to do it each time, and more than once I've accidently disconnected the call!

This does exist but there's often a lag and only some sites have it implemented.