We have DLT TC-416 telephone exchange switch in our office. We have 2 phone lines connected i.e. PHONE-LINE1 & PHONE-LINE2 and 6 telephones are connected inside the office. I want to configure it such that all the mobile phone calls e.g. 03331234567 which start from digit 0 (zero) should automatically use PHONE-LINE2.

If your system has a Block table, Block 0 as first digit on line 1. This is not automatic, but keeps calls using 0 as the first digit from dialing out on line 1.
Will be back if I think of something else.