706: The arbitration apparatus determines whether the high frequency band corresponding to the MODEM 1 conflicts with the middle frequency band corresponding to the MODEM 2. The arbitration apparatus determines, according to the preset correspondence table, whether the high frequency band corresponding to the MODEM 1 conflict with the middle frequency band corresponding to the MODEM 2. The preset correspondence table is described in operation 506 shown in FIG. 5. Details are not described herein again.

707: If no conflict occurs, the arbitration apparatus switches from the DSDS mode to the DSDA mode. If the arbitration apparatus determines that the high frequency band corresponding to the MODEM 1 does not conflict with the middle frequency band corresponding to the MODEM 2, it indicates that the voice service on the MODEM 1 and the data service on the MODEM 2 can be performed concurrently. Then, the arbitration apparatus may switch from the DSDS mode to the DSDA mode. In this case, the arbitration apparatus may allocate, to the MODEM 2, a service resource corresponding to the middle frequency band. The MODEM 1 continues to use the service resource corresponding to the high frequency band. In this way, the two MODEMs can implement concurrent transmission.

708: The arbitration apparatus sends a frequency band update acknowledgment message to the MODEM 2. In other words, the MODEM 2 is indicated to operate in a middle frequency band.