No Service - Restricted Network

Hi,

Till Saturday Sep 08, 2012, Network was working fine on my iphone 4 ( it's provider unlocked phone). I did some application update on saturday evening and I noticed that since sunday morning, My iphone is showing "no service".

When I tried to manually connect to career, it is showing me the error message " Restricted network - Your selected cellular network is restricted. You can choose different network in setting"

I tried various option like airplane mode on and off but no luck, still showing above no service message. I even tried network setting reset, reset all content and reset all but none worked.

Then, I restored my iphone to factory setting using itune. Still no luck.

My iphone got activated and I do see message that my phone is unlocked.

In setting -phone -sim application - I do see the name of my career "airtel" and all applications provided by the service provider too.

I don't know what went wrong and causing this no service issue. The same sim card is working in my other GSM nokia phone.

I went to airtel customer service center, they told me that it is problem with Apple iphone and few more people has reported the same issue today. All has been advised to go to apple customer center by career provider.

Could you please advise.

Appreciate your help.

for your ref. iphone is upto date with version 5.1.1(9B208).

Thanks

Anil