Oh, just for the record I'm on a monthly plan with Telecom and prepaid with Vodafone purely for the best mate add on.
My Telecom is $20 a month for 100 Telecom and any landline minutes, 25 Vodafone minutes, and up to 500 txts to anyone for up to $10 a month.
My Vodafone eats away at my prepaid balance, for a grand total of $6 a month
In my opinion the Telecom on plan rates are better if you call after 7pm or on the weekends. They have no daytime minutes included (and those cost $.89 or more.....0800 numbers are free though, see below). Vodafone does have daytime minutes, but their weekend minutes are significantly lower b/c of it. And to get the same as Telecom you have to get a few add ons, but that could make them more expensive.
ALWAYS USE AUTOLOCK. Otherwise after getting a few accidental $20 phone calls, you'll get into the habit anyway.
Oh, and one more tip - calling 0800 numbers is ABSOLUTELY free from your mobile. Doesn't matter what company, what time of day, etc. The companies that use 0800 numbers pay for you to call them (unless you get a message saying to call a local number, b/c they are too cheap to want your mobile call)