no free data plan help

Hi, I have no free data plan and would like to use internet services when I'm connected by wifi only.
If the phone connects to the internet via 3g etc then I have to pay.
Ive experienced this before and its wiped out all my pre pay credit very quickly.
What do I need to set to enable/disable this.
For example, I want to be able to use the GPS so Ive disconnected network help.
If I turn off data in the settings, then I cant use the wifi. The only way round this is to disconnect the network coverage and re enable the data setting. I can then use the internet on wifi only.
This is a pain, as I have to remember to re connect the network back up and disconnect the data.
Any way around this.
Also, is there anything else I have to set to be sure its not going to cost me.

Thanks in advance

Why not just disable "Mobile Network" in Connections?

I want to be able to still receive calls. If I disable mobile network, I cant while its disabled.

well, if you turn off data services in mobile network settings, you should technically still be able to browse internet through wifi easily.
however as i surmise, you actually want your phone to be connected to data services only when it's connected to wifi, well if i guess your issue right, i'm afraid there's no automatic solution to it.

You don't say where you are, but in Canada you can get a "no data" plan that won't allow data use on the mobile network. We also have plans that only allow BBM and email (unlimited) but no other data.

delete the service books for mobile network internet

Sent from my BlackBerry 9800 using Tapatalk