WhatsApp needs a phone function (SIM card) to register WhatsApp.
It is possible to use WhatsApp with a tablet or system (i.e. Veolo) without phone function but it is a bit tricky.
I made a How To in a Pad forum. unfortunately in German.
If that's no problem, there you can find it:http://www.android-hilfe.de/anleitungen ... annsi.html