I've seen a few mentions of people being able to check their Vodafone voicemail by ringing their own mobile number rather than the usual voicemail number.  This allows them to use their call minutes rather than pay 20 cents per time.  Since I'm on one of the new prepay plans that includes carry-over minutes I think that I'll be accumulating quite a few minutes as I don't often make many phone calls, so it would make sense for me to use this method rather than pay 20 cents per pop.

Does anyone have any instructions on how to do this?

The one time I tried it I got my usual voicemail message that I had recorded, but no option to do anything other than leave a message for myself.  Are there any special keys I need to press or something to get into my voicemail using this technique?