they are a 3rd party - reference checker
someone you know has given you as a reference - they are the company employed by the 'potential' employer to validate the reference.

It called me two times...

Three calls from this number in 2 weeks.  Final call left a message...from someone named Ryan Driscoll (spelling may be off) who stated he is from a company that has developed mobile apps for sports camps.  Message deleted without listening further.

I got tree calls from the number +0000000i a day for two days. Then number changed to +32000000 three times in a day. I don't know who it is and don't know fro, where and why they call