A system, a method for call processing and a device are provided. The device includes an IMSI and multiple MSISDN, wherein the multiple MSISDN includes a main-number and a sub-number, the sub-number is corresponding to an incoming call answering policy and an outgoing call number policy, and the device is capable of receiving an incoming call message carrying the sub-number and processing the incoming call message according to the incoming call policy corresponding to the sub-number and capable of configuring an outgoing call message according to the outgoing call number policy corresponding to the sub-number and sending the outgoing call message to a communication network.