Abstract: A method for allocating control time slots to terminals in a multipoint system based on time-division data transmission. Specific grant numbers are allocated to the terminals in downstream time slots. One grant number is associated with a grant to send information, such as one ATM cell, in corresponding upstream time slots. The terminal may be forbidden by means of a grant number to send in a certain time slot, or the time slot may be called a slotted Aloha time slot or a measurement time slot used for timing advance adjustment. The network terminal sends grant numbers at a predetermined rate to each terminal or sends grant numbers on the basis of how much information the terminals report needs to be sent. ATM channels are accessed rapidly and allocated efficiently, and a short access delay for a speech channel is achieved.