as above are you hoping that entering 1966 will disable it. If so would this not be used by burglars?
you can't disable it like that as its not a diy bit of kit.
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?