How are timeouts requested and timed?

Under World Aquatics rules (Part Six, Articles 3.10, 3.11 and 5):

Requests

• Each team has two one-minute timeouts per match.
• The Head Coach (or acting head coach) calls "Timeout" aloud and signals a "T" with the hands to the table or a referee, or uses an authorised timeout device from the bench.
• Valid only for the team in possession during play, or, during a stoppage, the team due to restart with the ball. Not allowed during a video review or between periods.

At the table

• The secretary (or a referee) who hears or sees a valid request immediately whistles to stop play. The match stays stopped for the timeout.
• The timekeeper times it and whistles (or uses another audible signal) at 45 seconds, when players may move anywhere, and at the end of the timeout.
• Play restarts on the Referee's whistle with a free throw on or behind halfway (or the pending penalty throw).

Invalid requests: by the team not in possession during play, the other team gets a penalty throw (no personal foul is recorded when a coach or team official called it) and the calling team loses a remaining timeout. By the team in possession with none left: free throw to the opponents on or behind halfway. During a stoppage with none left: no timeout.