Abstract: An communication system such as a host signal processing modem includes a host computer and a device that is coupled to communication lines and a host processor in the host computer. In a normal operating mode, the device generates periodic interrupts that cause the host processor to execute a software portion of the communication system. The software portion communicates with the device and implements protocols required to maintain communications with a remote system via communication lines. In a wait mode of the device, interrupts from the device to the host processor are suspended and selection logic in the device selects communication signal such as a ring signal from the telephone lines as an interrupt to the host processor. While in wait mode, a power management system can place the system in a sleep mode because the periodic interrupts are suspended and do not indicate system activity that would prevent use of the sleep mode.