I cant use another sim card on my iphone. It says sim card not supported

Your phone is carrier locked. You need to contact them to get your phone unlocked.

I need to unlock my phone to use another sim card

Your carrier.

I CAN NOT USE MY SIM, MY IPHONE SAYS THAT THE SIN CARD IS NOT SUPPORTED DUE TO SOME CARRIER. PLS HELP ME ASAP, I WANTED TO USE MY SIM.HOPE MY REQUEST WILL BE ACCEPTED FOR WHICH I WILL ASK MY ANDROID USIBG FRIENDS TO SWITCH TO IPHONE AND MY EXPERINCE WAS GREAT WITH APPLE.

Contact who?

The answer has already been posted on this page. Read through the answers.

Is your phone carrier locked? If so, you can only use a sim card from them.

Como puedo activar mi iPhone