A method for allocating radio channels in a quasi-transmission trunked mobile communication system including base stations and a first mobile station communicating with the base stations using radio channels, and at least one other mobile station requiring a radio channel. In the method, a radio channel is kept reserved for such a call in which the first mobile station is participating. This radio channel is allocated for the first mobile station for the duration of its call transaction. The first mobile station terminates and its call transaction, the radio channel is kept reserved for a predetermined time for the call. For accelerating allocation of new call transactions, it is checked whether the radio channel may still be kept reserved for the call. If the radio channel may still be kept reserved for the call, time-out time (T.sub.s) for a call transaction depending on the traffic load of the radio channels is calculated, and the channel is kept reserved for the time corresponding to the calculated time-out time, subsequent to which the radio channel is released. If the radio channel may no longer be kept reserved for the call, the radio channel is released.