A method for minimizing energy usage in a portable unit in a wireless communications system incorporates means to locally generate information on motion of the portable unit and to adapt a transmission from the portable unit based upon such motion information so that energy usage is minimized. By applying this method, information concerning motion of the portable unit is utilized in order to adapt transmissions from the portable unit in such a way that less energy is consumed. In the case of a portable telephone, connection time is thereby primarily increased, because it is then that most energy is used for transmission. In many cases standby time is also increased because many telephones also transmit information during standby, for example during so-called roaming.