A method of selecting a route for a session requested by a calling user equipment in a session manager in a communication network, comprising: a. receiving (S111, S121) a session request message for requesting to set up the session from the calling user equipment; and b. selecting (S113, S123) the route for the session based on load related information of a plurality of media gateways controlled by the session manager, the load related information being stored in multiple media gateway control functions, and the load related information including a ratio between a number of channels being used for sessions by the media gateway and a capacity of the media gateway, the capacity being a maximal number of channels that can be used for sessions by the media gateway; wherein the load related information of the plurality of media gateways is obtained by the session manager via said multiple media gateway control functions; wherein the step b further comprises: b21. Obtaining relevant information of the calling user equipment and/or a called user equipment from the session request message; and b22. determining at least one corresponding media gateway control function from the multiple media gateway control functions based on the relevant information of the calling user equipment and/or the called user equipment; b23. Selecting, from the at least one corresponding media gateway control function based on the load related information of media gateways controlled by the at least one corresponding media gateway control function, a media gateway control function from the at least one corresponding media gateway control function controlling the media gateway having relative lighter load to control the setup of the session, thereby selecting a route for the session; and b24. transmitting the session request message to the selected media gateway control function controlling the media gateway having relative lighter load. a. receiving (S111, S121) a session request message for requesting to set up the session from the calling user equipment; and b. selecting (S113, S123) the route for the session based on load related information of a plurality of media gateways controlled by the session manager, the load related information being stored in multiple media gateway control functions, and the load related information including a ratio between a number of channels being used for sessions by the media gateway and a capacity of the media gateway, the capacity being a maximal number of channels that can be used for sessions by the media gateway; b21. Obtaining relevant information of the calling user equipment and/or a called user equipment from the session request message; and b22. determining at least one corresponding media gateway control function from the multiple media gateway control functions based on the relevant information of the calling user equipment and/or the called user equipment; b23. Selecting, from the at least one corresponding media gateway control function based on the load related information of media gateways controlled by the at least one corresponding media gateway control function, a media gateway control function from the at least one corresponding media gateway control function controlling the media gateway having relative lighter load to control the setup of the session, thereby selecting a route for the session; and b24. transmitting the session request message to the selected media gateway control function controlling the media gateway having relative lighter load.