According to an embodiment, a communication device performs communication with a terminal device via a network and includes first and second connection maintaining units and a switch instructing unit. The first connection maintaining unit maintains a connection established with the terminal device and mediates communication between the terminal device and another terminal device. The second connection maintaining unit maintains a communicable state of the terminal device with the communication device according to a method different from a method implemented by the first connection maintaining unit. When a predetermined switching condition is satisfied, the switch instructing unit instructs the terminal device to switch a method for maintaining a communicable state either from a first method, which is a method implemented by the first connection maintaining unit, to a second method, which is a method implemented by the second connection maintaining unit, or from the second method to the first method.