Calling from Mumbai MTNL Landline to Mobile Numbers outside Maharshtra

i am trying to call some mobile numbers from my MTNL landline in mumbai. the numbers are based outside of mumbai ie in states other than maharashtra. when i dial the full ten digit number, it gives me BEEP BEEP sound for some time and then it says - pls check the code u are dialing. what am i dong wrong????? and is it not possible to dial mobile numbers direct from landline to other states. do i need to have STD activated in this case. Please Help.

Yes, you need to have std activated and you need to add zero before the cell phone number.

STD is now activated automatically.

All you need to do is set STD lock code. Once you do that, STD gets activated automatically.

http://mumbai.mtnl.net.in/telecomservices/phoneplusstd.html