I'm not sure why the previous thread on this topic was locked, but this is a very big deal for me as I have two SkypeIn numbers, one in Auckland and another in Christchurch.
I can confirm the poster's findings that if I call the number in Auckland via Telecom, I receive the number unobtainable signal. If I call the same number from my Vodafone mobile, all works fine.
However, the Christchurch number is working fine on both my Telecom landline and my Vodafone mobile.
I take it that the only way to get a resolution for all of us affected is to lodge complaints with Telecom Faults and Skype. Certainly an interesting situation.