What's the best way to set up my iPhone on a prepaid plan?

There are two types of cellphone networks; CDMA and GSM. The older iPhones like the 3G can only connect to a GSM network, which may limit you to certain carriers. Last I checked, Verizon was pretty much CDMA, and there were certain areas (like parts of Southern NH) where GSM service was unavailable. I mention this simply because what is available in some places may not be an option for you in Denver.

Oh, and a lot does depend on the SIM card.

Being on GSM, your options are pretty much AT&T or T-Mobile. I had a jailbroken iPhone and have been on both networks.

I’d say I HIGHLY prefer AT&T over T-Mobile and will pay the extra few bucks. With that being said, you sign a contract to subsidize the cost of the phone. Since you already HAVE the phone, you don’t need to worry about signing a contract as they will not require you to do it!

Just jailbreak if you want to get on T-Mobile, walk in, and get a plan. They will give you a SIM card and off you go. Or don’t jailbreak, get a SIM from ATT and off you go anyway.

Sadly, with an older iPhone your options are limited.

And trust me, no matter how hard you try, you aren’t going to get around being dicked by a cell carrier here in the US of A. You either get better service and pay more money, or not. . . the old adage definitely applies: You get what you pay for.

ATT was better for me b/c SO MANY people are on ATT that the free mobile to mobile allowed me to get the lowest minute plan and save a few bucks. I got a better deal with T-Mobile up front, but had to watch my minutes to make it worth it, so ATT was the wise choice for me.