A radio access gateway; comprising: a module configured to receive an access request from a Mobile Station, MS initiating a call via a radio access point; further the radio access gateway comprises a module configured to transfer the call to a corresponding function based on a service type contained in the access request; wherein: the radio access gateway transfers the call to a MSC/VLR in a Circuit Switched, CS, network, if the service type is a voice service; the radio access gateway performs route selecting, determines a Gateway GPRS Support Node, GGSN of called party of the call, and controls the radio access point to establish a connection with the GGSN, if the service type is a mobile packet service; and when the radio access point has been determined to be valid after being authenticated by the radio access gateway, the radio access gateway manages the radio access point to allow the MS to directly access the packet switched PS network through the radio access point by: the radio access point performing route selecting according to destination address of the service and establishing a connection to Internet, if the service type is a PS service indicating the MS requesting to access Internet; wherein messages borne by an interface between the radio access point and the radio access gateway are divided into messages of a user plane and messages of a signaling plane wherein the user plane distinguishes a CS message and a PS message and the signalling plane distinguishes a CS signalling message and a PS signalling message. a module configured to receive an access request from a Mobile Station, MS initiating a call via a radio access point; further the radio access gateway comprises a module configured to transfer the call to a corresponding function based on a service type contained in the access request; wherein: the radio access gateway transfers the call to a MSC/VLR in a Circuit Switched, CS, network, if the service type is a voice service; the radio access gateway performs route selecting, determines a Gateway GPRS Support Node, GGSN of called party of the call, and controls the radio access point to establish a connection with the GGSN, if the service type is a mobile packet service; and when the radio access point has been determined to be valid after being authenticated by the radio access gateway, the radio access gateway manages the radio access point to allow the MS to directly access the packet switched PS network through the radio access point by: the radio access point performing route selecting according to destination address of the service and establishing a connection to Internet, if the service type is a PS service indicating the MS requesting to access Internet; wherein messages borne by an interface between the radio access point and the radio access gateway are divided into messages of a user plane and messages of a signaling plane wherein the user plane distinguishes a CS message and a PS message and the signalling plane distinguishes a CS signalling message and a PS signalling message. the radio access gateway transfers the call to a MSC/VLR in a Circuit Switched, CS, network, if the service type is a voice service; the radio access gateway performs route selecting, determines a Gateway GPRS Support Node, GGSN of called party of the call, and controls the radio access point to establish a connection with the GGSN, if the service type is a mobile packet service; and when the radio access point has been determined to be valid after being authenticated by the radio access gateway, the radio access gateway manages the radio access point to allow the MS to directly access the packet switched PS network through the radio access point by: the radio access point performing route selecting according to destination address of the service and establishing a connection to Internet, if the service type is a PS service indicating the MS requesting to access Internet; wherein messages borne by an interface between the radio access point and the radio access gateway are divided into messages of a user plane and messages of a signaling plane wherein the user plane distinguishes a CS message and a PS message and the signalling plane distinguishes a CS signalling message and a PS signalling message.