Is there a way to completely disable the dialer including emergency calls to make an old phone a "tablet"?

I have a Galaxy Nexus (running 4.2.2 if it matters but I'd presume the rules would apply to most Android OS' in general, it isn't currently rooted but I can root it if necessary) that I've recently replaced with a newer phone. Now I'd like to give my 5 year old my Gnex as a basic "game/kids app device" that he can mess around with since he was used to playing a few kid games before on it. I still want WIFI access so airplane mode is out. However, **I'd like to be able to completely remove the PHONE functionality** from the phone. The phone has no service, but can still make Emergency calls and I'm concerned about him possibly doing so before I can explain to 911 that it was an accidental call. **So, is there a way to completely disable:** - the phone dialer - the ability to place emergency calls - the contacts/address book Bottom line: If you think in Apple terms, I'd like an "iPhone" to become an "IPod Touch", but for my Android.