A reader, JGH, from Washington DC commented on my How to Use Your iPhone 5 with Net10 Wireless guide.

I am looking to try this for two of my family’s iPhone 5′s unlocked from AT&T. Would I just follow the same steps, but use the old AT&T sim instead of T-Mobile? I understand there is a cap for data with AT&T (1.5GB).. Does Net10 offer 4G for AT&T or T-Mobile sims? This might be the deciding factor.. Also, does the sim switch method require that the sim (T-Mobile or AT&T) still be valid or is it just for pulling of smartchip/APN cellular settings? Thanks in advance, and thank you so much for the guide

He also added..

Oh, I am located in one of T-Mobile’s (and AT&T’s) LTE markets – Washington, DC. I’m just trying to rationalize if my unlocked AT&T iPhone 5 (model A1428) will work with BOTH the AT&T and T-Mobile sims from Net10, then which is “best” for me? Besides the data cap with Net10 T-Mobile, can you think of a reason why I SHOULDN’T get the Net10 T-Mobile sim if I am able to get T-Mobile LTE speed (4G) with this Net10 sim on my iPhone 5? Thanks again, Bob!

Hi JGM,
Thanks for checking out smartphonematters.com. It’s great to hear you are looking to see if you are  looking at prepaid phone services as a more affordable option. First, to answer your specific questions about the SIM swap for setting up MMS. If you want to setup MMS for an iPhone using Net10 on the ATT network, you will need a T-Mobile network SIM. The SIM card does not need to be active. You can setup both phones using the with the same SIM. The only reason you need this sim is to get access to the Cellular Data Network settings that are hidden when an ATT network SIM card is in your iPhone.

All of this is detail, Let’s take a look at your situation.

Choosing a Carrier and possible a Network too.

When you choose a prepaid phone service such as Net10 or Straight Talk you have the choice of using the AT&T, Tmobile, and even the Verizon network. These two companies are Mobile Virtual Network Operators (MVNO) and buy cell service from the big three and resell it.

So with Net10, you have a choice of using the AT&T network with a 1.5GB data limit or the T-Mobile Network with unlimited data. I have no direct experience, but I wouldn’t be so surprised if they throttle the data after a certain limit with the T-Mobile SIM.

For most iPhone users, the AT&T network SIM is the clear choice. You will get 4G HSPDA data, but not LTE. With the T-Mobile SIM,  you will get 2G Edge support. T-Mobile is building out their network with better support for 4G HSPDA and LTE support for the iPhone, but right now it’s in limited markets.

You mention you are in Washington DC and that T-Mobile has built out the network there. That is a good sign, I had a reader in Las Vegas, Nevada report that he got pretty good 3G and 4G service with Net10 on T-Mobile so it might be an option. I wouldn’t count on getting LTE though. The carriers have been saving it for themselves.

I can share with you that before I was on Net10 I had an unlimited T-Mobile prepaid plan I got 3G speeds close to Boston, but dropped to 2G Edge in the outlyng areas. Sometimes Google Maps with turn by turn directions stopped updating in slow 2G territory. So they exact areas you are in might make a big difference. Same if you travel. It’s something to keep in mind.

I’d also add that if I was considering Net10 on T-Mobile, I would look very closely at T-Mobile itself. They have a wider range of plans such as their $30 a month for 100 minutes and unlimited data. They have in-store support, MMS should be more reliable, you shouldn’t need to set it up yourself. Oh, and you have an iPhone 5 and the data service could be LTE.

My suggestion would be to go to T-Mobile and sign up for a prepaid plan for a month. Get an option with enough data service to reliably try it out. If you like the service, port your number and the second phone. You’ll need to switch SIMs around while trying it but in the end you’ll know if it works. If you don’t want to pay for s month of test time, at least ask to try a SIM in your phone in the store. Go when they are not busy. And you may want to do a iTunes restore on your iPhone before you go to make sure it is completely unlocked. Backup your phone first.

While you are at it, ATT Go Phone has a $60 a month 2GB data smartphone plan that supposedly supports LTE. I myself am pretty interested in that plan.

Finally, I add some other points you might want to consider in your choice.

Understanding your current costs.

You have two iPhone 5 s currently with AT&T. What is it costing you for those two iPhones on AT&T? If you have a Mobile Share Plan with the two lines with 1GB of data we can assume that at least $130 a month not including state taxes and regulatory fees.

Understanding your costs to switch
You mention that you have two unlocked iPhone 5 phones. Are you on an AT&T contract? If so you will need to pay and Early Termination Fee or ETF for each of the phones. That fee is $325 per phone. You can subtract $10 for each month of your contract you have completed. Since the iPhone 5 came out last September, the most you could possibly subtract for each phone is $100.

Understanding Your Goals for Switching

The obvious reasons to switch is to find more affordable service. You may look for a comparable plan that cost less, or a plan that is better suited to your needs that will result in saving money vs the ATT plan.

For example, two iPhones on Net10 with AT&T SIMs will cost you about $100 bucks. You’ll get 1.5GB of data for each phone which is more than with ATT. If you don’t require a lot of voice minutes or data you might want to look for a more affordable plan. At the most extreme, I have a friend with an iPhone on the T-Mobile $100 for a 1000 minutes a year, but no data plan.

Understanding What You Will Give Up

When you which to Net10 or Straight Talk you make some sacrifices in features and services. For example, your won’t have Visual Voice Mail. While it is possible, to setup MMS, neither company claims support. Setting up MMS yourself requires a little effort. And you may need to do it each time you update iOS on your iPhone. Most recently, many Straight Talk and Net10 customers using the ATT network have been getting Carrier Network updates that require them to go an set up data and MMS again.
On the service side, you won’t be able to walk into an AT&T (or TMobile, or Verizon, or Sprint) help. You will need to call or use the Internet for support. Most Net10 and Straight Talk customers I hear from report long wait times on hold.