# Call Progress Monitoring (CPM)

Call Progress Monitoring (CPM) is the method by which a unit such as the Catalyst RTU can interpret tones on the phone line to determine the progression of a phone call. Dialing and delivering notifications and data logs without regard to CPM is sometimes referred to as blind dialing.

In the Catalyst, RTU Call Progress Monitoring (CPM) is used to make decisions about whether to commence voice notification reports or whether to consider a call attempt failed, due to no answer or the phone line being busy. The RTU will operate quite differently, depending on whether CPM is ON or OFF.

The differences are as follows:

CPM ON (default)

- Notification, Status, Acknowledgement, and Log File reports are considered "FAILED" when there is no answer, or busy tones are detected.
- When CPM determines that a call has "FAILED," an appropriate entry is made to the log file, and/or the local printer (if selected).

CPM OFF (Blind Dialing)

- There is no such thing as a failed voice call attempt.
- If a phone number string includes tone detection characters, then the CPM dial tone detection capability will be automatically activated only for the tone detection and not for the whole call.

Important Note: The RTU will NOT make repeated attempts to the same number. The Redial Attempts feature is effectively disabled when CPM if OFF.