Spark has issued an immediate recall of its landline power back-up pack, because of a fire risk caused by faulty wiring.
It said 14,000 packs issued to phone customers were subject to the recall, and anyone who received and installed one since 22 March should unplug it immediately.
Spark product director Tessa Tierney said a customer recently reported their power back-up overheated and started emitting smoke.
"We immediately retrieved the device from the customer and put it through some testing.
"That testing actually showed us that there was a wiring fault in the device causing it to overheat."
Ms Tierney said after testing a random sample of other devices and finding other different but also concerning wiring inconsistencies, they decided on a product recall.
She said this problem was not a design fault, rather a manufacturing issue she believed was isolated to one bad batch of devices from China.
"We assure the public that they aren't under any immediate risk but we do ask...them to remove that power back up device."
Ms Tierney said Spark is proactively contacting all customers with the device over the coming days about the recall.
Customers are asked to either bring the power back-up to their nearest Spark store or contact Spark directly to arrange for collection.
Otherwise the devices should be stored in a cool, dry, ventilated place away from direct sunlight or water.
Ms Tierney said customers would receive account credit for the recall.