I bought a prepaid sim card for my Samsung galaxy s7 edge. The internet works but I cannot make or receive calls
Have you checked the APN settings or done a network reset as I assume you came from a different provider?
Have set the APN etc to the correct setting. As I mentioned I can access the Internet but not make or receive calls
Try re-inserting the sim and doing a restart and if that fails maybe try the sim in another phone if possible.