Nokia 3110 cellphone
Invalid IMEI no

I have bought a nokia 3110 handset around 2 years ago. I am using this phone under Airtel network. Few days ago I got a message saying that my handset's IMEI no is invalid and my handset will be rejected at 30.11.09. I have bought this handset from a authenticate dealer and my IMEI no is 355728021392755 and my mobile no is 9679674881. So please help me on this matter.

Yours faithfully,

Randip Ghosh