Does anyone know what this is/does? The handbook is delightfully vague.

Mine rings voicemail when I press it.

Mine too - I've tried editing its name but it won't accept any changes to the name

Yep - it's for quick access to VM messages............damned daft name for it though isn't it!

Not that daft...it's a mailbox for mobile voice messages?

Cheers, all.

I just saved my wife's number to it as a speed dial due to 'Mobile Box' being the first position on the touchscreen. She was in the car the other day and asked me "what's that Mobile Box name showing on the screen?".... I said, "That's your new name mrs"!!!