Galaxy nexus network issue! strange behaviour
I got a nexus from ebay the seller was from HK, i recieved the phone and everything works except for calls/texts. The phone just doesnt get the signal on the notification bar it always has a small x showing no service. Few strange things happened when i tried experimenting. I checked out all the forums and all possible solutions with no help.
When i insert a sim card and enter a APN there is still no network but i get internet from the sim card( i am sure im not connected to wifi). I get my whatsapp msgs but as i get my msgs the signal bar still shows there is no coverage.
Also when i put phone on airplane mode, in the lockscreen it says my networks name(airtel) and when i check my status it shows that there is some signal strength but im unable to make calls or texts or use stable internet.
I tried changing the baseband, tried all the global basebands with no luck.i flashed to 4.0.4 from googles official site too.
When i search for networks manually it shows my network along with a bunch of others but when i try connecting it fails.
Im attaching few screenshots of what i explained above, please help me out.