Your phone is locked to a mobile phone provider. You need to contact this mobile provider to ask for the unlock code (security code) for your phone. You need to provide proof of ownership etc and the phone's unique IMEI number which is located inside the phone under the battery. They use this number to generate the unlock code for your phone. They should provide you with instructions on how to enter this code into the phone. Once you unlock the phone, then you can insert a new SIM card in the phone.
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Your phone is locked to a mobile phone provider. You need to contact this mobile provider to ask for the unlock code (security code) for your phone. You need to provide proof of ownership etc and the phone's unique IMEI number which is located inside the phone under the battery. They use this number to generate the unlock code for your phone.
They should provide you with instructions on how to enter this code into the phone.
Once you unlock the phone, then you can insert a new SIM card in the phone.