Dear brother shuaib ahmed,
Its KRL. Its a strategic/defence organization of Pakistan and helps/supports the army. It takes atleast a week for an ordinary person to just "visit" the city of Kahuta because the place is highly classified and one must go through security clearance. Nobody can contact them or visit them or know who works for KRL unless "they" want you to know. The candidates who get selected must take an oath that they would not leak out what they do there. Their website becomes offline once the job offer expires. And you cannot contact them they dont list down any number there. If you got the sms then dont worry and go for the test with your documents.

Sent from my GT-I9300I