Hello,
I have a Blackberry 8120 Pearl, OS 4.5, T-Mobile provider, no data plan.

When I choose Wi-Fi only and am connected to Wi-Fi, the phone can still send and receive calls. As I understand the settings the phone should NOT be connected to the T-Mobile Network. When I am out of Wi-Fi there is no phone connection.
Worked about two hours with a T-Mobile tech rep and could not prevent phone action. We wiped the phone clean and did a reinstall of the OS, and calling/receiving was verified.
SETTINGS:

Options>Mobile Network>
Data Services= ON
Connection Preference=Wi-Fi Only
Mobile Network=T-Mobile
Network Selection Mode=Automatic

Manage Connections>
Mobile Network=OFF
Wi-Fi=ON
Bluetooth=OFF

If anyone is knowledgeable of this and can advise how to turn off the phone connection would appreciate the info.
Thanks,

Although I was not aware of it; it appears your 8120 has UMA.
Connection preference ONLY appears on blackberries with UMA.
UMA allows calls via wi-fi...hence why your able to call.
If you change the connection preference to mobile network, and keep the mobile network OFF and wi-fi ON; you'll still be able to surf the net, receive emails etc, but it shouldn't initiate UMA calling.

Can I ask which country T-mobile you are on? UK, US etc?

Ah magic.... Thanks for the answer. Yes, 8120 uses Edge and UMA. Neglected to indicate the UMA indicator when connected.

Am in the US.

If you do not mind and I am hijacking my own post, do you have any idea as to how I can find the host address for the Mapquest 4 Mobile phone application? Am using Aerize Wi-Fix to bypass the Google Maps and Mapquest requirement to have have a data plan.
I found the address for Google Maps but so far unsuccessful for Mapquest 4 Mobile.
Thanks

Unfortunately I don't.