Apple ipod

Is it really necessary g1 data plan if I put my SIM card in another phone?

Because no data plan needed, then right? And if I put my iPhone on T-Mobile T-Mobile charge me the same way? And I can use the G1 to go online when a 3G network in the vicinity? Please answewr of these questions

you do not have the g1 plan if you leave your iPhone. G1 using different servers. If you want Internet on your iPhone, then tmobiel CLAL and ask for the total package Internet. and request data and MMS settings. and can not use its 3G netowrk if G1 does not have a SIM card and has no data plan.

T-Mobile Sidekick Prepaid Plan on iPhone 2G/3G/3GS