In the other position connection is made between the common terminal and the other traveler terminal.
Remember that a three-way switch is actually a single-pole, double throw switch. The three-way switch has no ON or OFF position, which is why there are no ON or OFF markings on the handle of the switch.
Caution: To prevent severe shock or electrocution always turn the power OFF at the service panel before working with wiring.
Never Assume the power is off! Always double check, and test the device before you begin work.