What's a will call?

You need to wait and they will call out your name when there is availability. Like stand by for an airplane ticket

http://lmgtfy.com/?q=What+is+a+will+call%3F "will-call adjectiveUS relating to or denoting a place (typically a ticket window or office) where items that have been paid for in advance can be picked up. 'those picking up tickets at the will-call window must use the Trumbull entrance'"