Of all the advice I;ve see so far, the one that makes the most sense
was the person questioning why you need to know the old remote access
code to change it. The ones that I've had were set on the base unit
and you could do it without knowing the old code.

No way in hell I'd spend hours rigging crap to try to salvage a 20 year
old answering machine when you can buy a new one for $20