Sim Card/ other questions.

[jcwilson]

I was recently given an iphone 4 from someone who no longer uses it. I have used an old flip phone for years and have been reluctant to get one of the newer fancy phones. Now that I have an iphone 4, I am a bit clueless on where to go from here. I am interested in the Family Mobile plan that Walmart has with T-Mobile since it is affordable. This plan requires a Sim card.

1. What is a Sim card?

2. A colleague told me that my iphone 4 does not take sim cards. Do some phones use a sim card and others not use the card?

3. The phone was originally through Verizon (I think). Does this mean the iphone I have will only work with Verizon or can I use it with another service provider, such as T-Mobile/Walmart plan?

Thanks for your help.

 

[willerz2]

1) A SIM card is basically an ID for your device. It withholds your SMS, contacts, etc. It's a medium to allow your carrier to recognize your device in particular, and who the user/subscriber is.

2) It depends. There are 2 types of iPhone 4's (in general), the GSM and CDMA models. GSM requires a SIM for the iPhone 4. CDMA does not use a SIM for the iPhone 4. One way to check for sure which iPhone 4 model you have, is to look at the right side of the iPhone 4 (with the screen facing up as a reference point). If you see a little pinhole on the side of it, you can insert a paper clip or a SIM tray key to pop open the SIM tray to put your SIM. If it's not present, you have a CDMA iPhone 4.

Then to make sure that it's an iPhone 4 and not a 4S, look at the top of the phone where the headphone jacks are. Right next to the port, do you see a black band to the immediate right of it (have the screen facing towards you as a reference point). If you do not see a band next to the jack, AND there is a pinhole on the right as seen above, then you have an iPhone 4 CDMA. If you do see a black band AND a pinhole, you have the iPhone 4 GSM. If you do not see a band BUT there is a pinhole on the side, you have the 4S.

3) If your iPhone 4 (presumably) is a CDMA 4, meaning no SIM tray, you can only use it on Verizon or Sprint, whichever CDMA network it's on. Only with the GSM model can you unlock the device for use with other carriers such as T-Mobile.