A method for arranging the transmission of packets between a mobile communication device and a mobile communication network comprising: setting up by the mobile communication network at least one temporary block flow (UL TBF) for transmitting data in packets on one or more packet data traffic channels PDTCH in a first direction from the mobile communication device to the mobile communication network comprising: receiving a packet channel request message from the mobile communication device; allocating radio resources for the at least one temporary block flow; and transmitting a packet uplink assignment message containing information on the allocated radio resources to the mobile communication device, receiving by the mobile communication network data in packets from the mobile communication device by using said at least one temporary block flow in the first direction; at the end of the transmission in the at least one temporary block flow in the first direction, receiving by the mobile communication network information in the last packet from the mobile communication device about the end of the packet flow, and acknowledging by the mobile communication network the reception of the packets, and including by the mobile communication network a final ack indicator FAI in said acknowledgement; characterized in that the method further comprises: waiting by the mobile communication network a determined time after the end of the transmission of packets in said first direction until the transmission of said acknowledgement, and if, during the waiting time, the mobile communication network detects a need for transmission of packets in a second direction from the mobile communication network to the mobile communication device, setting up by the mobile communication network at least one packet data traffic channel PDTCH for data transmission in said second direction comprising using radio resources allocated for said at least one temporary block flow to transmit a packet downlink assignment by the mobile communication network to the mobile communication device. setting up by the mobile communication network at least one temporary block flow (UL TBF) for transmitting data in packets on one or more packet data traffic channels PDTCH in a first direction from the mobile communication device to the mobile communication network comprising: receiving a packet channel request message from the mobile communication device; allocating radio resources for the at least one temporary block flow; and transmitting a packet uplink assignment message containing information on the allocated radio resources to the mobile communication device, receiving a packet channel request message from the mobile communication device; allocating radio resources for the at least one temporary block flow; and transmitting a packet uplink assignment message containing information on the allocated radio resources to the mobile communication device, receiving by the mobile communication network data in packets from the mobile communication device by using said at least one temporary block flow in the first direction; at the end of the transmission in the at least one temporary block flow in the first direction, receiving by the mobile communication network information in the last packet from the mobile communication device about the end of the packet flow, and acknowledging by the mobile communication network the reception of the packets, and including by the mobile communication network a final ack indicator FAI in said acknowledgement; waiting by the mobile communication network a determined time after the end of the transmission of packets in said first direction until the transmission of said acknowledgement, and if, during the waiting time, the mobile communication network detects a need for transmission of packets in a second direction from the mobile communication network to the mobile communication device, setting up by the mobile communication network at least one packet data traffic channel PDTCH for data transmission in said second direction comprising using radio resources allocated for said at least one temporary block flow to transmit a packet downlink assignment by the mobile communication network to the mobile communication device.