Can you send and receive texts? Have you tried manually connecting to a different network? It should not work but did you set call barring while roaming? What plan are you on?
Just wanted to check in with you to see if you were still having issues receiving calls. Let us know
I had a similar problem: all was fine in Mumbai (voice, text, data), then in Hyderabad I got on the IDEA network and could not do data (I think texts work, did not try voice). What worked for me was to turn off 3G, which I did on my cheap Android phone by choosing "GSM Only" under Mobile Network Settings. I am now on Reliance and things are working well again.