there are 'algorythms' for answering machines too, that is if you don't mind sitting there for 10 minutes on the phone inputting the entire thing. I don't
I don't know how well those algorithms would work these days. Back in the 80's and 90's, answering machines weren't that smart. They would just wait to hear the right tones. They had no idea how many tones you entered and would completely ignore any wrong tones. Some had a time limit and some didn't. But very few had the ability to tell you that you hit an incorrect digit.
These days most answering machines and voicemails recognize every number you punch in. If it's a 4 digit code and you start off with 1 wrong digit, you have to start over. The algorithms would be useless on this kind of system.