invalid sim card while activating iphone5
I bought an iPhone 5 second-hand and everything is fine with it except when I try use my SIM card.
I get the message on the lock screen saying, "Activation Required" and then when I open the phone I get the message,
SIM Not Valid
The SIM card that you currently have installed in this iPhone is from a carrier that is not supported under the activation policy that is currently assigned by the activation server. This is not a hardware issue with the iPhone. Please insert another SIM card from a supported carrier or request that this iPhone be unlocked by your carrier, Please contact Apple for more information.
so please help me to fix this problem
iPhone 5