Problem with my Samsung Galaxy Core LTE


Hi guys ,I'm not really good in english so forgive me if I make some mistakes. I have got a Samsung Galaxy Core LTE and from yesterday I can't make calls and can't send messagges. The strange things is that I can receive them. When I try to call it goes in the call screen with the written "Composition...",meanwhile it doesn't rings, it stay like this for hours. When i press the "Terminate" button the "call" doesn't end but with the "Home" button I can use my phone (with the call open). The only way to close it is turn off the phone.For the messages it does the loading wheel. When I restart the phone it says the messages wasnt send correctly (with the written "Failed"). I dont think is credit problem but im not sure 100% because for know the credit i have to call a number (I cant call this number too). I can receive calls and messages from people with my service provider and from people with another service provider.