Some embodiments provide a method of determining whether a lottery player or the player's computer is within a particular location. The player's computer is connected to a computer network. The method transmits, through the computer network, a pass code and a telephone number to the lottery player's computer. The method requests the lottery player or the player's computer to call the number and provide the pass code within a pre-determined amount of time. The method determines whether the pass code is provided within a predetermined amount of time after the transmission of the pass code from a telephone specified to be within the particular location. The method verifies whether the lottery player or player's computer is within the particular location, based on the determination.