Activated Prepaid SIM help

[jordolang]

I just received my new iPhone 3G jailbroken 3.1.2. My plan was to go grab a GoPhone and activate it and put the SIM in the iPhone. Well the iPhone is constantly "searching" for service. I have read like 30+ posts on using a prepaid SIM on an iPhone. Well I was stupid and activated the SIM in the store to the prepaid phone.

I am currently erasing all data and settings from the iPhone. My question is when it is finished, what exactly do I do to get the iPhone working on the already activated Prepaid SIM.

My other question is once I get everything working, is it safe to upgrade to 3.1.2 jailbroken, or will my I run into the same problem I am having now?

Any advice would be very appreciated. Thank you.

[Sk8r789456]

Get a new sim

[jordolang]

The cheapest phone I could find was $29.99. I used to work at Radioshack and sold AT&T. The SIM cards we used in post paid phones were the exact same SIM cards that were in prepaid phone packages. Now they are completely different, they are GoPhone SIM cards. So in order to get a new SIM card, I am assuming I got to go buy a new phone. Unless I can buy just the SIM card, put it in and it will be activated as a pay as you go when I activate it... Any thoughts?