"To accept the call" means being willing and ready to take on a responsibility, task, or opportunity that has been offered or presented to you. Full definition
Available as assigned to accept calls in a professional and courteous manner. (simplyhired.com)
They usually pick out of indie published authors, not agent - submitted; don't call them, they'll email you asking you to accept a call if they want you. (madgeniusclub.com)
We will accept calls until all 40 spots are filled. (ccspca.com)