No network coverage sony ericsson k800i

How can get net work coverage in k800i sony ericsison mobeile phone

My phone sonyericsson w800i sim card accept the phone and display the network airtel, hutch ect. but call from other phone disappear the tower

I have k800i and the problem is no network coverage what will i do for this problem please help us

First try to insert the Sim-card properly in your Sony Ericsson K800i phone. Then go the network settings and select the manual network option and search for the network. If still the problem persists then carry the phone to the Sony Ericsson galley or the service center.

Go to network options
and check if automatic selection is checked
if not please do
and if u are sure about ur operator and its band and other settings.
perform manual settings
and then restart the phone
it should be done.
If u have prob. even
please send me why and how this all started