you can read this thread http://qatarliving.com/node/4658881
and this blog Live in Qatar
Both will help you about the credentialing, etc

Working in Qatar would mean a different Credentials Verification Process. The best thing is to follow up the HR if all documents are received. Because sometimes, they don't check. Especially if your documents were emailed, you should know the date when those documents were emailed by your employer because if you ask to follow up, they will ask of the date it was emailed.