It maybe your phone line converter. If it has comms in the queue it will keep retrying.
dissing is disconnecting
if you have dissed one of the legs then its not the device hogging the line.
When you say engaged what do you mean, I took it to mean it was dialling etc?
the from alarm pair is an open close clean switch to show the paxton if its armed or not.
the to pair will go to a zone programmed as keyswitch momentary