Development on an unlocked phone without having a service from mobile company

I am currently locked with a black berry plan but want to start development on Windows Phone 7. Obviously I can test my app with emulators but other option is to buy an unlocked phone. My question is that if I buy an unlocked phone and don't get any service from a mobile phone company, will I be able to connect to my WiFi and test things like location based feature of my program ( like list of local resturants)? Are there any things that I will not be able to test unless get a service from mobile phone company?

I've developed several apps now without putting a SIM card in the phone - so you can do it. You just need to be careful with:

• a false sense of speed - wifi is much faster and more reliable than 3G.
• a lack of testing for "real phone interruptions" - e.g. notifications of incoming calls, SMS messages, etc

As a first step, you can also develop on the emulator with no phone at all - but additional things are missing there (GPS, accelerometer) and certain things are slightly different again (e.g. resources load faster, the screen sometimes draws faster)