Subscription service will let users keep tracks even when it ends.
Nokia has signed a deal with Universal Music to offer unlimited music downloads for a year on phones carrying its Ovi web services.
Users will pay a subscription to download DRM-free music, which they can keep even when the yearly subscription ends.
Universal, which is owned by Vivendi, is the world's largest music group, but Nokia said that it is in discussions with other music companies about adding artists to the service.
Nokia said that Ovi, which means 'door' in Finnish, is designed to act as a gateway to a series of services and content.
Omnifone, which provides unlimited music downloads in partnership with Vodafone, Telenor, Hutchison Telecom and Vodacom, said that it welcomed the announcement.
"Consumers will increasingly come to expect unlimited access to music direct to their mobiles," said Omnifone chief executive Rob Lewis.
"We are delighted to hear that Nokia intends to embrace and develop its own version of the unlimited music download model which we launched in February 2007."
Competition in the music downloads industry has heated up recently. Pepsi is rumoured to be offering a billion free music downloads next year in a link-up with Amazon's online music store.
Omnifone claimed that it is in "active discussions" with the major labels about extending its existing music licences.