Hi sim newbie here. When are the cases where you would cut a sim card yourself? Im thinking of switching from tmobile to the go smart 35 plan (anyone have any reviews on it?) and go smart wants me to buy a new sim card...is this necessary? I'm keeping the same phone so not sure why I'd need a new sim. Thanks
Chops, on the GSM end, your phone service with your carrier is tied to the SIM card you place in your phone, and not the phone itself. You need a new SIM card from the carrier of your choice when you switch, in your case GoSmart, otherwise you can't activate an account with them.
Do keep in mind that before you can switch carriers, you need to make sure your phone is "carrier unlocked". If you bought your phone from T-Mobile and you're no longer under contract or owe money on the device, just contact technical support and they should give you the instructions and codes to enter to do this step so you can use your phone with any GSM provider of your choosing. If you're under contract still, given some of the other folks difficulties getting T-Mo to do this, you might be better off waiting or paying a third party service (plenty on Ebay) to do it for you,
but only if the phones were bought before January 2013. Phones purchased after this date are now illegal to carrier unlock without the selling carrier's express permission.
Why do you need to do this? Because without doing this step first, the best case scenario is that you won't be able to configure data settings with your new provider (T-Mobile MVNO SIM cards will work in T-Mobile carrier locked phones, but data won't work - same with AT&T MVNOs and AT&T phones). The worst case scenario is that you'll stick the new SIM card in your phone and it will bark that it's an invalid SIM and you wont get any service at all (this is what happens when you stick an AT&T SIM card in a T-Mobile carrier locked phone and vice versa). Confused yet? Don't worry. Re-read it slowly, and keep in mind that just like with the contracts and ETF fees, the carriers do this to try and keep you from switching in the first place. You untangle this, and you'll be free of their tenterhooks. Any other questions along these lines or unrelated to needing a SIM cutter,
bring your questions over here.
Back to answering your original question:
When are the cases where you would cut a sim card yourself?This one's easy.
SIM cards come in an assortment of sizes, the most common being the 2FF Mini SIM size (this is the size that most MVNOs sell), but there's also 3FF Micro and 4FF Nano sizes that are most commonly found in Apple iPhones, but are not exclusive to them as the smaller form factors have been adopted by some higher-end Android devices as well. If you need these smaller sizes and you're not crafty and adventurous or you can't find one the right size being sold directly or via Ebay, then you'll probably need a SIM cutter. Have a handy flowchart if you're still unsure!