This little chip identifies your account to your carrier's network.
The SIM card is often found lurking underneath the battery of many phones or mobile hotspot devices, and can be carefully slid out with a fingernail. For devices that lack removable batteries, the SIM is usually in a tiny ejectable tray that can be removed by pushing a pin carefully into a pinhole.
If you move the SIM to another compatible unlocked phone or device, you are essentially transferring your service (including your phone number) to that new device.
This can be extremely handy – you can take a SIM from a Mobile Hotspot and put it into an iPad, for example.
Or…you can keep an old beater phone around for when you are heading out into rough conditions – such as a backcountry hike or kayaking. Before you head out, just pop your SIM into the old device and you can still keep online and get phone calls, without putting your flagship expensive smartphone at risk.
Or…when you are traveling internationally, rather than paying expensive international roaming fees, you can instead get a SIM (and a local phone number) from a local cellular company, and then get online much, much cheaper.
Or...if you have a grandfathered in unlimited Verizon data plan that must be tied to a smartphone, you can move the SIM from the phone to a mobile hotspot or tablet device to get around paying an additional fee to tether.
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SIMs have been getting smaller over the years – the original full-size SIM from the early 1990's was the size of a credit card!
But the ones you are most likely to see today are:
- Mini-SIM / 2FF (now often called "standard" or "regular" size)
- Micro-SIM / 3FF
- Nano-SIM / 4FF
They are all electrically identical – so it is actually possible to cut down a Mini-SIM to put it into a device that has a Nano-SIM slot.
And you can use a small plastic cradle to put a smaller SIM into a Mini or Micro slot.
TIP: For a good list of what SIM sizes are used by many popular phones, look here.
Some people have been known to modify SIM cards with razor blades or scissors, but for less than $10 on Amazon you can buy a SIM cutter tool to make the process easier.
- The QQ-Tech Nano Sim Card Cutter has worked well for us - cutting both Mini and Micro SIMs down to Nano-sized.
- For more flexibility, a fancier cutter (like this Kaisi Universal 3 in 1 Cutter) can trim Mini to Micro as well.
For going the other way and using a smaller SIM in a device with a larger slot - we have used the Silver Hill Tools Adapter Tool Kit, and there are many more options to choose from on Amazon as well.
Cutting a SIM can be scary the first time - especially if you have never seen it done.
A word of caution for the 6620L JetPack: In particular when swapping a SIM card into a 6620L JetPack can be more difficult than others. For one, the slot is tighter, and some other SIM card sizes are actually thicker. You do need to lightly sand down the NON-electronic side of the card for it to fit. For more information on swapping into a 6620 (including a quick demo video), and what to do if you get your SIM card stuck: Opening up a Jetpack® 6620L to Remove a Stuck SIM card
To help demonstrate how SIM cards can be cut down and sized-up, we created this video guide: