Now that smartphones have GPS it would be easy to automatically divert incoming calls to answer phone and disallow outgoing calls when the phone is moving above walking speed. They could make this an automatic function that cannot be shut off except for calling 999 (say your passenger is reporting a drunk driver whilst you are following). Not sure if this would work or is even desirable as it would shut off use on trains (not a bad thing in my mind) and also would not work if your phone couldn't get a GPS lock.
Yeah but how would I use my phone and cycle at the same time ?