This is not the first time that Indian Telecom giants (BSNL) site have been hacked and defaced. Today, just a minutes ago, Pakistani hacker with the online handle, "P4K-M4D-HUNT3R-Z" have hacked and defaced two sub-domains of BSNL. The sub-domains belongs to the "Value Added Service" and another belongs to the "BSNL International Roaming".
As like other deface site from Pakistani hacker, which contains the message belongs to free Kashmir, this one does not carry any kind of message like this. Rather its just have the Security warning.
At the time of writing the post, site is still showing the deface page. You all can check the mirror of hack at Zone-h also.
Hacked website and Mirror: