To select e.g. to a sports squad.
To summon (someone) to report for military service.
To retrieve from personal or computer memory.
To call on the telephone.
An order to report for military service.
To add one's own name to the list of people who are participating in something (including amateur, but not professional, teams)
To agree to purchase some good or service.
To add a name to the list of people who are participating in something.