Work Permit

Hi, I am an Indian and have received an offer from an company registered in Thailand and head quartered in Singapore. As per them, they will hire an external agency to process y work permit in order to Work in Thailand. I just wanted to know how can i make sure that this company is eligible to process my work permit before resigning from my current company.. as there is a clause in the offer letter saying that the offer stand's still only in case i get the work permit. A kind help on this matter would be much appreciated.