Tax payers are already forking out for the interest on the bonds used to fund the building of the NBN.
NBN Co has received about 5b in funding as of 12/12. That's an annual interet bill of 200+ million. When it is fully funded this will grow to 1+ billion. Considering oz bond rates are below their long term trend, that's 2+ billion when things return to normal.
Conroy is smoke & mirrors - I wouldn't trust him with my kids' school lunch money.