Sony BMG will provide content to Nokia's Comes With Music programme in the second half of 2008, the company announced.
Nokia Comes With Music was announced last December, and combines a mobile phone with a year of unlimited access to music.
Sony BMG is the second record label to jump on board after Universal Music. Its roster includes artists such as Alicia Keys, Britney Spears and Bruce Springsteen. Nokia has said it expects all major labels to join.
The Finnish phone giant has said it hopes the service will add new revenue for the benefit of artists, labels and other rights holders.
Several questions remain, however. Nokia still hasn't announced where the service will launch, and on which phones.
Nokia recently denied reports that it will pay Universal Music $35 for every phone that offers the service. The actual sum is still being negotiated, according to a spokeswoman.