[Lagged2Death]

How do you type your password into your telephone, something this system has to support?

There's a lot of speculation in the thread that this is the reason, and it's not a totally unreasonable guess. If this is the reason, then you're right, my scheme would not be suitable.

While we're all guessing, though, I think there are reasons to doubt a "password via DTMF" requirement. Look at the other rules: Passwords are case sensitive, must contain both letters and numbers, and "Cannot use proper names," whatever that actually means. None of those makes any sense with DTMF, where any string is non-uniquely reduced to a string of digits. Passwords are also limited to 20 characters, which is just as arbitrary with DTMF as with anything else.