Avaya
The company that likes to keep your phone/user name logins database on the Avaya servers that any consultant setups up, in plain text (not the consultants fault, its Avaya's shitty software). So all you have to do is steal the database and you have access to everyone's Avaya user name and password logins. The user names and passwords that 99% of people end up using for their AD logins, so you now have compromised their AD account as well.
Oh and go with a full PC/Laptop client only and forbid desk phones and you have "Sorry I know you're dying but I need to login to Windows first before I can call 999. Oh...sorry...hold on...I now can't remember my password. Oh, sorry, you're fucked now as I've locked my account so now can't call 999 for you".
And "Why did I take ages to answer your call? Because I couldn't answer the fucking thing until I logged in. And by the time I put my long password/passphase in, you rang off".