Just create a script that reads your customer records, and uses the place call step to call each one back sequentially.
label get next record
read record for contact info and days until expiration
if record is not empty
true
place call to contact info
success
play prompt your warranty is expiring in X days
terminate call
goto get next record
failure
goto get next record
false
end
You will need some way of kicking this event off. the easiest way is to setup an HTTP trigger on your app, then have a scheduled task hit that URL at a certain interval.