A reminder to retailers selling 3G devices, that customers should be fully informed of the network shutdown at the end of the year

Spark, 2degrees and One New Zealand are all closing their 3G networks.

That will affect a range of devices, including mobile phones, webcams, health alarms, alarm systems and other industrial devices.

Paul Brislen -- the Chief Executive of Telecommunications Forum industry organisation -- says consumers should double check with the seller, than the product they're buying is fit-for-purpose.

He says new tools will be available soon, including a number you can text to check whether your phone will still work after the shutdown.