step by step help please from Iphone users

[Dragoonxgears]

I'm currently on the $30/5gb data plan.

I'm using a Lg optimus right now, and I just bought a jailbroke Iphone 4s on ebay.

I went to the tmobile store to ask about the micro sim. They told me as long as I buy $20 in accessories they will transfer my current phone number to the mirco sim.

What I want to know is, what is the next steps.

can I just put in the micro sim into the iphone then plug it into itunes?
I also read about changing the settings on the tmobile website.
is there anything i'm missing.

How do I avoid Itunes from updating my iphone and removing the jailbreak?

when I have the time and money, I will get the phone unlock permanantly so no need for jailbreak.

thanks in advance for all the help anyone can give.

Hope the refarming of the network comes soon to my area.

[overdrive31]

You have a Gevey Ultra S sim? I don't see the reason for jailbreak otherwise. You cannot unlock any ol' phone with just a jailbreak. A locked iPhone 4S requires a Gevey Ultra S sim or a carrier unlock to work with Tmobile.

You can block OTA update badges with No Update tweak from cydia. Just avoid restoring/updating in iTunes, it's not like you plug in and it updates, it requires interaction.

You can cut the sim down to micro, then get an adapter to use with phones that use mini sim, so you can swap the sim with other phones.

Changing cellular settings is easy with a jailbroken phone, just install a Commcenter patch or TetherMe and you can change all the settings. If you don't jailbreak, it's a little more work to get Tmobile settings entered.