With on-hook programming, you can access the programming mode of the telephone without going off-hook. On-hook programming works with the following telephones:
With on-hook programming, signaling changes from dual-tone multifrequency (DTMF) to S-channel. The timeout period for this change is 60 seconds. For non-display telephones, signaling remains DTMF, and the timeout period is 10 seconds.
