For example, in the USA you could check if an AT&T iPhone is unlocked simply by borrowing a T-Mobile SIM card, placing it in the iPhone, and seeing if the device gets service. Either use a friends SIM card or visit a T-Mobile store and they’ll be able to check for you.
http://osxdaily.com/2013/06/17/check-iphone-unlocked/
To check your MTN Sim card registration simply send REG as an SMS to 789 and you will receive a response that will show you the status of your Sim card registration. Glo Sim registration Check. To check You Glo Sim card registration simply. Send REG as an SMS to 3456. to know if you Sim is registered or not. Etisalat Sim Reg Check. To Check If Your Etisalat SIM Has Been Registered. For Etisalat, you can verify your SIM card registration status by calling 200 or sending an email to care@ etisalat.com.ng. Airtel Sim Reg check.
http://www.xtremeloaded.com/6469/check-sim-registration-status-on-mtn-glo-etisalat-airtel
How to Find a SIM Number The subscriber identity module, or SIM, card is the small card in your mobile phone that provides the phone with its network... How to Unlock a PUK Code SIM Card A PIN Unlock Key or Personal Unblocking Key (PUK code) is a unique number that’s used to unlock the Subscriber Identity Module...
http://www.ehow.com/how_6184343_do-check-sim-card-number_.html
Find the iPhone IMEI number by dialing *#06# on the phone – you do not need cell service to dial that number, the iPhone just has to be turned on. If the *#06# trick doesn’t work, you can also find the IMEI from iTunes, on the back of iPhone 5, on the devices SIM card slot, or through the iPhone itself as described here.
http://osxdaily.com/2013/06/17/check-iphone-unlocked/
your SIM card is your memory card which stores phone numbers photos and info about your phone whhen your phone tells you to check your SIM card all you have to do is locate it (usually under the battery of your phone) turn your phone off, take it out and reinstall it then turn your phone back on it should work fine.
https://answers.yahoo.com/question/index?qid=20061122200345AAmkq5O
Check Phone Number. Here is that let you more easy to check and manage your account as below when you purchased the EG SIM card directly from the selling points nationwide including GS25 or got a free EG SIM card from the our special events. Check Balance for Voice & Data. Check Usage for Voice & Data.
http://www.egsimcard.co.kr/eng/myaccount/check-special.asp
Turn the cell phone off. This keeps your important information safe. Turn the phone over and slide the battery cover off. This may take a bit of pressure, but don't force it, as it may damage the cover. Remove the battery and place it aside. You will see the SIM card resting beneath where the battery was.
http://www.ehow.com/how_6184343_do-check-sim-card-number_.html
Method 1: The Easiest Way to Check if an iPhone is Unlocked: SIM Cards. By far the simplest way to determine if an iPhone is unlocked or not is to swap in another GSM provider SIM card, wait a moment or two, and see if the iPhone gets service. That’s all you will need to do, but this assumes you have access to another GSM SIM.
http://osxdaily.com/2013/06/17/check-iphone-unlocked/
How to Find Your PUK Number A Pin Unlock Key (PUK) is a code assigned to your cell phone's SIM card by your service provider. If you have... How to Save Messages to SIM Card SIM (subscriber identity module) cards hold your mobile service subscription information on them and identify your account to your mobile phone.
http://www.ehow.com/how_6184343_do-check-sim-card-number_.html
SIM, you probably need to check the SIM card. its in the phone usually behind the battery. Just see if you can take it out and then put it back in. if that doesn't work you may need to take it back to where you got it...or see someone from your service provider. energizerbunnygirl05 · 1 decade ago.
https://answers.yahoo.com/question/index?qid=20061122200345AAmkq5O
how to check sim card status
To check your MTN Sim card registration simply send REG as an SMS to 789 and you will receive a response that will show you the status of your Sim card registration. Glo Sim registration Check. To check You Glo Sim card registration simply. Send REG as an SMS to 3456. To know if you Sim is registered or not. Etisalat Sim Reg Check. To Check If Your Etisalat SIM Has Been Registered. For Etisalat, you can verify your SIM card registration status by calling 200 or sending an email to care@etisalat.com.ng. To check your MTN Sim card registration simply send REG as an SMS to 789 and you will receive a response that will show you the status of your Sim card registration, for Glo Sim registration check send REG as an SMS to 3456, to know if you Sim is registered or not on Etisalat Sim Registration Check, you can verify your SIM card registration status by calling 200 or sending an email to care@etisalat.com.ng.