I honestly can't believe how much I've written in this comment about such an insignificant annoyance from a few years. Consider it self-therapy that I accidentally left on HN.
I previously had a phone on Vodafone in the UK, and infuriatingly their voicemail system would not allow you to delete a message until you had listened to it for either 3 or 5 seconds, I can't remember.
Most of my messages were either spam calls I knew would have left a voicemail from when I rejected them, or my dad who has finally learned that I'm just as likely to call him back from seeing him in my missed calls list and therefore he no longer needs to leave a "Hey, it's me calling, feel free to call back or not" every single time. (It took several years of begging him to not leave a message unless he either a.) had a piece of information he wanted to give me in that message or b.) there was a time sensitivity beyond normal conversation.)
So for each message you wanted to delete, you had to listen to the robotic voice say "Caller, oh, eight, hundred, [pause], seven, etc etc etc, called, today, at, twelve, fifty, seven, PM, [pause]" then the message would start, you wait what you think is the right amount of time before pressing 3 to delete, and if you get it a fraction of a second too early, not only does it not delete it, but it tells you (in those slow, monotic, robot, words) "I'm sorry, but you cannot delete this message until you have listened to at least three seconds." AND THEN IT WOULD START AGAIN FROM THE INTRODUCTION TO WHAT FUCKING NUMBER HAD CALLED AT WHAT TIME.
Man, that's like therapy, writing that out. My mobile number was quite publicly available, included in press releases that were googleble, etc. so I got a fair few spammy voicemails. Thankfully, eventually either I discovered or their system added, the ability (bug) that if you press 3 (the delete button) almost immediately after the end of the robotic words "message deleted", you could time it so the system knew you had already deleted the last message, but hadn't reset the clock for how long you had to listen to the next message for, so once you knew the rhythm you could delete them in about 5 seconds each without being stuck listening.
