Abstract: A method for using femtocell as a telephone exchange is provided. The method comprises the following steps. A femtocell registers to a core network via an Internet. The femtocell receives a phone call, and determines whether the phone call comes from the core network or the internal network. If the phone call comes from the core network, then the femtocell automatically answers the call and provides a prompt. The femtocell determines whether an input number of the phone call is an internal extension number. If the input number is the internal extension number, then the femtocell transfers the phone call to a corresponding internal extension.

Abstract: A radio signal transmission method is used in a radio signal transmission system having a core network (CN), at least one base station and at least one user equipment (UE). After the UE initiates a circuit switch (CS) call, the base station determines whether to activate CS off-loading. If to activate CS off-loading, the base station determines whether identification (ID) codes of all call parties reside on the same base station or on the same group of base stations of the system. If yes, the base station determines whether to off-load only the user-plane data. If yes, the CN controls the signaling and the user-plane data is directly forwarded to another call party; otherwise, the base station processes a signaling and the user-plane data is directly forwarded to another call party via the base station.

Abstract: A method for integrating UE functions to a femtocell is provided. The method comprises the following steps. The femtocell with a subscriber identity module (SIM) is activated. The femtocell reads the information of the SIM. Based on the information of the SIM, the femtocell registers to a core network via an Internet. The femtocell having successfully registered to the core network provides SMS service, MMS service or Call service.

Abstract: A radio signal transmission method is used in a radio signal transmission system having a core network (CN), at least one base station and at least one user equipment (UE). After the UE initiates a circuit switch (CS) call, the base station determines whether to activate CS off-loading. If to activate CS off-loading, the base station determines whether identification (ID) codes of all call parties reside on the same base station or on the same group of base stations of the system. If yes, the base station determines whether to off-load only the user-plane data. If yes, the CN controls the signaling and the user-plane data is directly forwarded to another call party; otherwise, the base station processes a signaling and the user-plane data is directly forwarded to another call party via the base station.