The 0800 number for the automated system to take redcare offline is 24 hour - it requires your EIN and some numbers off the back of your security ID card - it gives you a recorded message when done stating that redcare is now disabled, and reminding you to recommission it when work is done - there is no other procedure that I have been made aware of - sometimes this doesn't seem to work though (my one and only point)
Redcare is out of band signalling that monitors the telephone line - if the equipment at BTs end detects no response (/monitoring signal) from the equipment at the customer's end, it triggers the system - the idea of which is to notify the authorities before setting any alarms off (to catch them red handed, hence redcare) I would never leave site without checking that the system is back in service, by contacting the alarm company direct with my and the customer's details - some other engineers are unable to do this as they work on the network and not within customer premises - they are still supposed to leave everything as they found it, but if they can't access the premises and obtain the customer's details they can't necessarily check with the alarm company that it's working - they will however ensure that the redcare is back on, and notify the customer that their telephone line is back in service - who should then contact the alarm company...
Being in the position of being with the customer in their premises when I'm working, I fortunately can check everything works before I leave, rather than rely on automated systems - you won't catch somewhere I've been in no response afterwards.