I also wonder about CPC. Cable company phones line will typically provide that, I can hear the talk battery cease for about a second after the called party disconnects. I just set up an ATA 190 to test and get familiar with it. I added the second line. I thought I saw somewhere that indicated some parameters for the second line are set from and therefore the same as the first line, but I can't find it again. Maybe that was a different device. I also searched on the web GUI of the ATA for CPC, or something related, didn't see anything.
Currently, when the called or party disconnects, a few seconds later a fast busy is heard, no interruption of talk battery. I'm thinking of using this with a paging interface that answers the ringing line and connects the audio to the page amplifier for a predetermined amount seconds. I haven't been to the site to look at the interface, probably a Valcom model. I know some can be set to disconnect upon loss of talk battery (ideal) or - fast busy, or after a few seconds of silence. I can recall being somewhere when after a page complete. the very brief beginning of the fast busy tone could be heard before the connection was released, so the fast busy disconnect would be a last choice.
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After posting this I changed the Reorder Delay from 5 seconds to 25. It was then 25 seconds after the calling line disconnected before the fast busy was heard. That should suffice for silence detection if the page adapter has it.
