Device and Method of Handling Dual Connectivity

A network for handling dual connectivity comprising a first base station (BS) and a second BS configured to perform the following instructions:

• the first BS configuring a radio resource control (RRC) connection with a communication device via a first cell of the first BS;
• the second BS transmitting a secondary cell group (SCG) configuration to the first BS, wherein the SCG configuration changes a SCG;
• the first BS transmitting a RRC message on the RRC connection via the first cell to the communication device, wherein the RRC message comprises the SCG configuration;
• the first BS receiving a RRC complete message from the communication device via the first cell or a second cell of the first BS, wherein the communication device transmits the RRC complete message in response to the RRC message;
• the first BS transmits a complete message to the second BS in response to the RRC complete message;
• and
• the second BS starting scheduling at least one transmission for the communication device, when the second BS receives the complete message and the SCG configuration indicates the communication device not to perform a random access procedure.