Can I easily disable cellular data on an Android device and just use Wi-Fi? Does this change based on whether or not I have root on the device?
Yes. It is possible to fly under the radar. I have done this on AT&T and T-Mobile in the USA.
CDMA2000 providers (Verizon, Sprint) will instantly catch you because to activate the phone you have to provide the ESN - which they will look up.
For AT&T, I switched to an unlocked phone (OpenMoko FreeRunner) a while back, so AT&T isn't sure what phone I have - the site says "We don't recognize your phone." I'm now using an HTC Magic (T-Mobile MyTouch 3G) that's unlocked. I have data disabled and only turn it on to send MMS. I have used data with their "WAP.Cingular" data plan. It's EDGE and it's a penny a KB, but it does work (I've loaded a few websites to test mobile data.)
My wife, best friend, and his father all use G1's with data turned off on AT&T and they do not pay for data plans.
All our contract terms are expired - we're month-to-month and can leave at any time.
The website doesn't recognize my phone because AT&T does not issue the Dream or Magic, this may be part of the solution. Using an AT&T phone on AT&T may be inviting trouble.
Keep your data turned off and never tell AT&T what phone you have, and you should be fine. Change your useragent in your browser (Cyanogenmod has a way to fake some old Nokia, that's what I use).
For T-Mobile, I'm using a G1 on their Pay-As-You-Go plan (it's a backup phone for running, SIM is usually in an old Motorola candybar). They know I have the G1, but a data plan isn't available at all for PAYG. As I don't use the phone this much, it's acceptable.
YMMV, buyer beware. It's possible, though.
How to disable cellular data
You can open the “Tester” application by opening the phone dialer and entering the number
(It is easy to remember as
The carrier I use for my kids' phones does not allow me to disable cellular data from the carrier side, so I use this method to turn off cellular data on their phones.
As others write, several apps exist to accomplish the same, but doing the way described above does not leave an app on the phone that allows the kids to accidentally turn on data again themselves.
Thank you to these guys:
This is where I found the information after searching the net for a long time.