Trustpower is to offer mobile phone services and wireless broadband through a wholesaling deal with Spark New Zealand.
The electricity, gas, phone and internet provider said it will work with Spark to develop the new products in coming months.
"Trustpower has been seeking access to mobile services for some time, and is delighted to have secured a wholesale supply arrangement with Spark," said Craig Neustroski, the firm's general manager for markets.
"Mobile is increasingly important to our customers, and the ability to offer it as part of our household services bundle is exciting."
Trustpower shares rose 2 cents to $6.44, taking their gain this year to 7 per cent.
The company has offered phone and internet services since 2007 and began offering gas in 2013 as part of a strategy to target more valuable customers and discourage them from changing supplier.