PBX Gaurdian

I was thinking about writing a small module for something closely related.
I would like to have a daily wellness check to elderly who are living alone and who opt-in in the system.
I've heard too many stories of people who fall and are staying on the floor for days before being rescued by a neighbour who worried about the mail overflowing from the mailbox.

The idea is call each person every day, at an approximate fixed time they have previously chosen when enrolling, and to ask them to enter a 1 if everything is ok, a 5 if they want to change their subscription to the service, a 9 if they want to talk to someone.
In case of no answer or timeout, another call is send an hour later. If no answer again, the caller is flagged and an email/phone call alert is sent to an alternate number.

The option 5 can be used to let the subscriber to change the hour of the day for the call, or to suspend the service for a few days, or to leave a message in a voice mail of the program administrator to add some information on the person's file.

The problem I see with using the call file is to manage busy channel (either in the pbx or on the subscriber side). The context should be able to detect that the call was not placed and create a new call file. Also after too many busy signal from the subscriber it should also flag a warning.