Call routing from several queues to a single agent?


I intend to have my agents logged in several queues. Each queue is figuring a skill (for instance a language skill).

I can’t find the answer to the following question : If there are calls waiting in the different queues where is logged my agent, how the call is selected among the different queues.

Is it random, round robin, the most waiting one? How the call is selected if several queues (with the same weight, the same priority) can offer calls to the agent?

Thank you for your help,