Grantis:A well balanced post & a very good point to bring up about how a NEW customer is defined, especially in Telecom's case as they don't utilise SIM cards. It would be interesting to know how it all really works.
Vodafone define their customer base on their number of active connections - ie contract customers + any SIM card that is active. So they could well have a large number of prepay connections that are still valid (ie haven't reached their 1yr cutoff in which case they will be diconnected).
I believe Telecom count their customer numbers in exactly the same way. I know a few years ago when things were going very poorly for them they actually stopped disconnecting unused prepay connections simply to boost their customer numbers! It was one of the quarters when they got something like 20000 new customers and I heard at the time that if they had not made the decision to keep those prepay accounts live they would have actually lost customers in the quarter.