iphone5 problems in receiving and making calls, iphone5 problems in receiving and making calls

I have been facing issues in making and receiving calls on my iphone5 device.

The calls do not get through, takes lot of time in getting back to the home screen once the call is disconnected.

At the sametime, if tries to call me, my number gets unreachable.

Have spoken to my service provider (Vodafone) as well, but there's no issue at their end.

Pls let me know the solution.