ok ill use english i dont know how to type from sinhala...
There is a Thing called Number portability which was introduced to srilanka in 2007 comes in 2010
http://en.wikipedia.org/wiki/Local_number_portability read the Srilanka section..
Simply means You can keep your existing number and change you network operator.. will say you have 071000001 which is mobitel @ the moment..
and you can move that number to a dialog package if you are the owner of that number.. according to the new policy the number belongs to you..
So the thing is dialog blaster gives 1000mins free to 077 numbers and mobitel gives free 1000mins to 071 numbers ...
now this way the network gets confused because a mobitel user can be on a 077 number as well.. thats y they have stop issuing those packages..
they will arrange some thing like a universal database or so.. Which currently they have if you dial #132# they will arrange some good packages no idea so must wait and see...
For more about number portability its on the TRC site
http://www.trc.gov.lk/component/content/article/48/143-mobile-number-portability-eoi.html