Dear, Abdel! the Queuing works for MOC and for MTC both and for handover also. MSC indicates in Assighnment Request (TCH assighnment) to BSC that queueing is allowed. When there is no idle TCH on radiointerface then Ass Request shall be put in a queue and BSC shall send the Queuing Indication message to MSC and start timer. After succesful TCH allocation within period defined by timer, Assighnment Complete is transfered from BSC to MSC. If implementation dependent queuing timer expires then BSC sends Clear Request to MSC and removes Assignment Request from queue.