Any Samsung Galaxy Note 7 smartphones that have not been returned soon won't work, except as wi-fi only devices.

New Zealand phone companies will blacklist Samsung's fire-prone Galaxy Note 7 mobile phones in two weeks.

The policy means any of the smartphones that have not already been returned to Samsung or its distributors will no longer be able to be used to make calls, send texts or connect to mobile broadband.

Samsung issued a global recall for the phones last month after dozens of reports they had overheated and caused fires or burns.

Telecommunications Forum chief executive Geoff Thorn said while most of the devices had been returned, it estimated there were still a few hundred in the hands of Kiwi consumers.

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The forum, which represents the country's phone carriers, said they had decided to blacklist the phones because of safety concerns, with Samsung's agreement.

Samsung Note 7's won't work on any of New Zealand's mobile networks, after November 18, the forum said in a statement.

"Numerous attempts by all providers have been made to contact owners and ask them to bring the phones in for replacement or refund," it said.

The smartphones would still connect to the internet via wi-fi, and could be used offline.

But blacklisting the devices from mobile networks should help ensure the remaining handsets, which were in the "low hundreds" were returned, Thorn said.

The smartphones had previously been banned from planes and from being put in the mail.

Phone companies are able to block phones from connecting to their networks because each device has a unique 15-digit code, called an IMEI, that is checked automatically each time a device attempts to make a connection.

The same technique is used by Spark, Vodafone and 2degrees to block stolen phones from their networks.