im on a telstra phone plan, which i am contracted to for 24 months (1 year to go), paying $40 a month, i am on a sh|t call rate but excellent sms's, so when i make some calls my monthly bill sky rockets!
i have enquired about going on a telstra cap (the $49), you pay a bit higher call rate and normal sms rate but get $200 odd worth of calls and people on them, swear by them (Bec!!).
i looked at switching to a cap, but becuase i have a phone plan, i am paying off the phone on the contract, so i would be paying about $70 a month rather than my $40, worth it if my monthly bills these days are around $70 but as they have been ranging up to like $68 (not including last months of $97!!!) - its not worth it!