This application provides a communication method, apparatus, and system, and relates to the field of communications technologies, to improve a success rate of receiving a paging message by a terminal device. The method includes: After determining a target first cell, determining to reselect a first cell, or determining to have reselected a first cell, the terminal device sends first information to a network device. The first cell belongs to a first network. The network device belongs to a second network. The first information is determined by the terminal device. The first information includes first configuration information and/or first timing offset information. The first configuration information includes to-be-used gap GAP configuration information or to-be-used time division multiplexing TDM pattern configuration information of the terminal device.