The phrase "call off bets" typically means to cancel or withdraw bets that were previously made. Some antonyms for this phrase may include "place bets," "keep bets," "maintain bets," or "uphold bets." These antonyms imply the opposite action of canceling or withdrawing bets, and instead suggest keeping or placing bets as originally intended. In some cases, the opposite of calling off bets may also include raising the stakes, making additional bets, or doubling down on existing bets. Ultimately, the antonym for "call off bets" will depend on the specific context and circumstances of the betting situation.