Well id imagine most companies would have top shelf disabled anyway.
I have a company phone and a personal phone and I agree with
@Scam, if your company appears to be a good business to work for and you have permission to use the phone for 'personal use' and whatever that may involved I can't really see it being a problem.
Why not send an e-mail to HR or your Line Manager asking them if its OK to use the phone for personal use and if so what restrictions (if any) they may have?, if they say sure its OK no restricts then you surely have nothing to lose. If in 12 months time they say you have broken the rules on using your company mobile phone, you will have an email that you can show them to say that you had permission. If they ever did end up sacking you or going down the disciplinary action route, you could potentially sue them for unfair dismissal.