Sub-group communication during a direct mode of operation of mobile stations in a mobile communication network. A controller in a mobile station detects a request to transmit an outgoing communication and determines whether a push-to-talk key is in an activated state or in a deactivated state. The controller further selects a first power level when a determined state of the push-to-talk key is the activated state, and selects a second power level when the determined state of the push-to-talk key is the deactivated state. The controller also transmits, via the radio unit, the outgoing communication on a current operating channel to at least one other mobile station within a mobile communication network at the selected power level.