Awhile back when I got my cell phone, I reprogrammed the voicemail number. I programmed my phone so that when I dialed voicemail it would dial the VM number, pause, and then hit a "1." I don't remember why I programmed it to do this, I believe it makes it skip past the time stamp or something.
Well time had come that I no longer needed the appended "1" -- so I went spelinking through the internet to try and figure out how to change it.
It turns out your voicemail number is programmed in 2 places on your phone. Both in the "speed dial" slot, and the "call forwarding" slot. This second time around, I reprogrammed the "call forwarding" slot, not the Speed Dial slot.
The problem occurred when people tried to leave me a voicemail!
But first, a 30 second primer on how voicemail works.
When you get 'sent' to somebody's voicemail, you're really having your call forwarded away from their cell phone and into a voicemail center. The voicemail center reads the caller-ID of the incoming call, which should be the caller ID of the person's cell phone, and from that it knows what voicemail box to send you to.
(Side note -- This is also a security flaw. If you have your voicemail set so that you do not have to type in your password every time you call, than if somebody spoof-s your CallerID and calls the Voicemail center, it will freely grant them access to your voicemail box.)
Now your phone has several call-forwarding options. The 2 that get used for Voicemail are "Forward if Unanswered" and "Forward if Unreachable."
Forward if Unanswered is obvious, and is the number that your get forwarded to if your phone rings, and you do not answer.
Forward if unreachable is the number that your caller gets sent to if your cell company can't access your phone, whether it's off or out of service.
For voicemail to work as you'd expect it to work, both numbers need to be identical.
Sooo, in my reprogramming palooza, I changed my "Forward if Unanswered" number. The problem was, apparently, I set the wrong voicemail center.
Because I set the wrong number, when people called me, the call that would get forwarded to VoiceMail was arriving with THEIR phone number, instead of MY phone number. This meant the system either didn't know what to do with you: "Please enter the voicemail box of the person you are calling" or, if you happen to be on the same Voicemail system as me (AT&T in Salt Lake), it just dumped you into your own Voicemail: "This is Richard..."
Anyway, long story short, I got it fixed. Here are the codes.
To set call forwarding when unanswered:
Time can be "05,10,15,20,25,30" depending on if you want it to wait 05,10,15 seconds. I have mine set to 30, because sometimes it takes me a long time to answer my phone, and I hate it when I miss the phone call by 2 seconds. (This also means if you call me and I'm in a test, or otherwise unable to answer, sometimes it rings F-O-R-E-V-E-R. Sorry. Deal with it.)
To set call forwarding when unreachable:
To set the voicemail-speed dial code on the iPhone, and any GSM phone I'd imagine:
Now you know.