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February 22, 2017

In search of a prepaid, transferrable SIM

At, we often analyze and report on mobile computing devices with integrated WWAN (mobile broadband) capability and a SIM card slot. SIM (Subscriber Identity Module) cards are smart cards that contain a subscribers phone number and certain data. Initially just used for the early GSM (Global System for Mobile communication) networks, SIM cards are now also used by carriers that based their networks on the rival CDMA (Code Division Multiple Access) technology, like Sprint and Verizon. However, those vendors use SIM cards only for 4G LTE.

Anyway, it would be nice for us to be able to test device wireless data capabilities while we review them. We can't always ask vendors and manufacturers to get us test units with activated voice and data service, and we cannot, of course, set up cellular service for every such device that comes into our lab. So I wondered if there is an equivalent of prepaid phones and cards for SIM cards. That way, we could load a SIM with so and so many minutes or gigs of data and then simply insert it into a SIM card slot for testing. And then transfer it into another device for testing when the need arises.

Problem is, there is a difference between prepaid phone cards and SIMs. With a prepaid phone, you buy minutes of air talk time for a particular phone and the prepaid cards simply replenish the allocated minutes for that phone. SIMs, on the other hand, contain your phone number and contacts and such, which makes the SIM inherently portable. The phone number and data on the SIM goes with a certain account and certain network, and so, presumably, as long as you had minutes or a data allocation on a network, you ought to be able to transfer SIM cards between devices that have SIM card slots.

Online search yielded conflicting information as to whether there are prepaid SIMs and if so, whether they could be inserted into another device without having to go through the hassle of setting up service again for the new device.

So I went to WalMart. They had aisles and aisles of phones and prepaid phones and prepaid phone cards, but just a single "SIM kit." It was not apparent from the packaging how it would all work, how minutes or data would be purchased, or what it would cost. I asked the folks at the electronics counter, and they not had no idea.

I tried Best Buy next. Best Buy, too, has a very large number of phones from various vendors and for various networks. I explained our situation -- that we needed a prepaid SIM that we could move from device to device for testing of their communications -- and the answer was twofold. First, Best Buy only sells phones and carrier service, not cards and prepaid stuff. Second, such a thing as I needed did not exist.

This seemed unlikely to me. The only difference between a prepaid phone and a prepaid SIM would be that with a SIM you could take your phone number and contacts and other data from one phone to another; service on the carrier side would be the same: so and so many minutes or so and so much data is allocated to a particular phone number.

So I went to Walgreens. Lo and behold, they had three SIM card kits, each costing $10 for which you got a nano SIM card with adapters for use in devices that take the larger micro and standard SIM cards. Of the three, the GoPhone kit looked the best, with its packaging claiming to work both on iOS and Android devices, and also showing "refill and go" cards on its package. Further, GoPhone uses the AT&T network that we already use at RuggedPCReview.

Back at the office I browsed through the voluminous documentation that included a frightening amount of fine print, the kind leads to the modern problem of never really knowing what something actually ends up costing. Or what extra charges would be added for this, that, and the other thing. Yes, there were 18 pages of AT&T legal fine print. Annoying.

But I did follow the basic directions, stuck the tiny nano SIM card into the standard SIM adapter that our first test device required, and then used a WiFi connection to go to and set up an account. I was pleased to see that nothing but an email was required, name not mandatory. Which, given that there is no contract and it's all prepaid, seems appropriate. I quickly got an email back with a phone number associated with my new SIM, and a request to now log on and pay. That, of course, instantly required a name and the usual detailed personal information. So goodbye (relative) anonymity), and can't you guys just give me the full scoop right upfront?!

And it's really not just buying minutes and then using them until they are gone. An AT&T account is required and you have to sign up for a service and the service automatically renews every month, etc., etc. You CAN purchase refill cards and that, presumably, avoid using credit cards or automatic bank payments. So I'll look into the refill cards just for the sake of it. However, what I wanted most, a SIM that had so and so many non-expiring minutes on it, that I didn't get. Whatever you don't use you lose, and every month there's a new charge even if you didn't use the phone for even a single call. Boo!

Anyway, the device worked just fine. But after being done testing it, would I be able to transfer the SIM to another device with a different operating system? I tried that by going from an Android device to one using Windows 10 Mobile. It worked. No fuss no muss, the new device simply had service and worked just fine. These two devices, however, had virtually identical (or identical) hardware. What about putting the SIM into a different handheld or smartphone?

I tried that with another Android device of a different make and a different version of Android. And that one used the micro SIM format instead of the standard format. I found that popping the tiny nano IM card in and out of its fragile plastic adapter isn't something one wants to do very often. And also that most SIM card slots obviously weren't made for frequent insertion and removal of cards. They are very fragile.

But the device came right up. No problem. What is confusing these days is figuring out what uses data and what still uses minutes. Most phone plans have now been changed ot data plans, but the inexpensive phone-only plans still use minutes. And that's what the (relatively) inexpensive GoPhone plan does. So the phone wants to know if data use is permitted? No, I guess not. But it still shows data use as on, which greatly raises paranoia of stepping into one of the phone companies' many gotcha traps.

The phone, however, works. And so far I've been able to transfer the SIM from one unlocked device to another without any issues.

Posted by conradb212 at February 22, 2017 09:03 PM