I was curious about your question so I tested it with an android phone I have that was not being used with any mobile network. I have a Verizon OG Droid that belonged to my daughter. She upgraded to a Droid 4 in February and her mobile account was moved to that cellphone. So the OG Droid was left in a "clean ESN - ready to be activated to Verizon" state. I just got it out of the closet and tried to use it with our house wifi (cable high speed internet access). It found the wifi network quickly and logged in fine when I put in the wifi password. The router assigned the OG Droid a proper IP address and I can get online with the normal browser and access google, amazon, etc on normal wifi speed. I also went into the cellphone settings and purposely disabled the "Data Enabled" selection of the "Mobile Network" option just to ensure that it would not even try to access the Verizon data stream even though it should really not be able to do so since there is no active Verizon account attached to this cellphone. The wifi worked flawlessly throughout. Then I tested out some apps that essentially require data access to operate properly, like Amazon Appstore and Youtube. They also loaded and ran absolutely fine. Now, the OG Droid is a 3G device only and not 4G capable. I don't know if the wifi connection of a 4G cellphone would work in the absence of connection to a mobile data network since I don't have a 4G cellphone to test with. I only mention this because 4G cellphones require a 4G simcard to work (at least the Verizon ones do) and I don't know if that may impact wifi connections when the mobile (Verizon) data stream is not accessible. But in my test, the 3G OG Droid definitely can establish a wifi connection in the absence of access to a mobile data network.
