Cannot make calls in iphone 4 with OS 4.3.3

I am having apple iphone 4 with 4.3.3 software update. It was working fine till yesterday but I don’t know what happened. I am able to receive call and send text messages but I am not able to make outgoing calls since yesterday. Whenever I try to make any call, I get a call failed error message. My iphone 4 is actually unlocked and I am using Airtel Network (india) service. I would like to know why this thing is happening to me. Any suggestions for the same would be highly appreciated. Thank you in advance.

Well I can give you a simple suggestion that you can try. First try to remove the sim card from the phone and put it back again. Now try to make calls. I hope it works but if it doesn’t then I think you must contact the airtel service provider. Go the airtel gallery and ask them to rectify your issue. I hope you are allowed to make calls. You can also call the customer care and take the guidance on the phone itself. Obviously for this you have to use someone else’s phone. Try to restart the phone. I think if the issue has come after the software update then I would recommend you to upgrade or downgrade the software update on your iphone. Try installing some other update. Nope check whether the problem has resolved or not. If all this doesn’t help then I think you can contact the apple guy’s ti help you out. May be your call settings have got changed. Ask them about this. Try to see it by yourself once before you go to the apple. Go to the settings option and there look for the call settings. Set it to default and try. I hope it helps. If it doesn’t then reply back to me so that I can give you some other solutions. All the best

well i have faced the same problem with my iphone. i think that the update has nothing to do with that. i was having a different update but this happened with me too. i still dont know the solution . i sold off my iphone.