How to forward to voice mail

Hello, I'm trying to figure out a way to explain what's happened:

The gist of it is that I had my voicemail set up fine, and
accidentally cleared all forwarding and now I've been unable to set my
phone so that it goes to voicemail when people call me and I'm not
around.

I set up the forwarding as the voicemail number, that one 822-1123?
(Toronto, ON).  Anyway, the point is now when I'm not available people
are getting this thing which just asks for your mailbox number...
seems like this is the number for *checking* messages, not *leaving* a
message.

What do I have to do to set that up the *leaving* message again?


Thanks