So it costs 20c to check voicemail.  Does it matter if I ring 202 or +64222022002?  i.e. does calling the second number result in "mobile" call cost or "voicemail" call cost?

I've just switched to 2degrees, so it's a bit new to me.  Previously my mobile calls were "free" (i.e. included) and I never used them all so I would use a mobile call (free) over voicemail call (20c) any day.  Now I'm paying for each call, if a voicemail call is 20c for however long it takes vs 22c/44c per minute or part thereof I'd rather use a voicemail call.  Does that make sense?  So, can I use either number or best to stick to 202?