Hey jers007! Right now there's no way for a phone to register a missed call unless it's on, because when your phone's off, the call routes to the voicemail system. Since the call doesn't actually connect, there's no charge for it - but also no record of it as a completed call in the system (unless a voicemail is left). I'm not sure if there would be a way to alert a customer of calls that didn't complete; but it's definitely an interesting idea and we appreciate the feedback! Are you thinking about this as being useful in a situation where you have to turn your phone off - perhaps at work - rather than just keep it on silent?
Manage your T-Mobile account