People using iPhones on Telecom's XT network or on 2 Degrees new network have been warned they will lose tethering capability if they upgrade to Apple's iPhone3.1 software, released overnight.
Tethering allows users to use their phone as a modem for laptop internet access.
"Do not download it if you require tethering, but go right ahead and update if you don’t," the iPhone New Zealand blog warns.
According to the blog, Apple now signs the access point names (APNs) within the carrier bundles.
"This means if there is no signature against the tethering APN it will not work (all other functionality is fine though). We are working on a fix for this and as soon as we have it the bundles will be updated and we’ll let you know."