Patent ID: 8391469

Claim:
An apparatus comprising: a tone detector to detect a start of a first tone of a dual-tone signal; a first counter to count first cycles of the first tone when the first tone is detected; a second counter to count second cycles of a system clock while the first counter is counting the first cycles of the first tone and the first count of cycles is less than a first threshold; a third counter to count third cycles of the system clock when the first tone is detected; state control logic to start the second counter counting third cycles of the system clock when a time period elapses, the third count of cycles of the system clock being substantially equal to the second count of cycles, the first counter to count fourth cycles of a second tone of the dual-tone signal while the second counter is counting the third cycles of the system clock; and a decoder to compare the fourth count of cycles to a second threshold to identify an event represented by the dual-tone signal.