- Network locked, what to do?
- What is network card - Guide
- Cannot ping computer on same network - Guide
- Network error occurred - Guide
- Ubuntu reset network settings - Guide
- Send popup message to another computer on network windows 10 - Guide
It seems that your phone is locked by the carrier. Either it can only be used in the U.S. or only with the network of the same carrier.
You (or your cousin), must contact the carrier associated with that phone in order to unlock it. Once it is unlocked, you will be able to use any SIM card.
CCM can't help you to unlock it, as stated in this article.