Well guys..
I searched for the topic in nokia site and got the following info.
I hope this will help you understand Line 1 line 2..
:
:
Line in use (network service) — this setting is shown only if the SIM card supports two subscriber numbers, that is, two phone lines. Select which phone line (Line 1 or Line 2) you want to use for making calls and sending short messages.
Calls on both lines can be answered irrespective of the selected line. You cannot make calls if you select Line 2 and have not subscribed to this network service. To prevent line selection, select Line change > Disable if supported by your SIM card. To change this setting, you need the PIN2 code
