My iphone is working but not taking incoming calls? Any thing ican do to fix?

When i call my iphone from another phone it rings but nothing comes up on the iphone also i cant call out from the iphone, when i call nothing happens. Any ideas?

Added (1). Is working! Can still use apps and whats app to send msgs

Well, it's not really working then, is it!
If you have an Apple store nearby, call in and speak to one of their advisers. The staff their are very friendly and helpful and I'm sure will fix it for you quickly.