Move over Spotify, there is a new music service in town.

Muve, a phone-based music plan sold through Cricket Wireless, offers unlimited song downloads for $10 a month, inserted unnoticeably into a customer's monthly cellphone bill, which ranges from $55 to $65. In many ways its users defy the conventional profile of a digital music consumer. They are young and urban, yes, but instead of a laptop or a tablet, they use a phone for everything. Most earn less than $35,000 a year and lack credit cards, so they prefer Cricket's month-to-month cash plan.

According to information from the New York Times,

Since its introduction in January 2011, Muve has signed up 600,000 users, putting it in the league of Rhapsody, which has about one million subscribers, and Spotify. (Spotify has four million paying users in 15 countries, but has not said how many of those are in the United States.) And Muve is poised for another growth spurt with a new line of phones that the company believes could bring in millions of new users.

"Cricket's customer is young, is ethnic, and tends to be middle and lower income," said Jeff Toig, the senior vice president of Muve Music. "This is not a segment of the market that the major technology companies innovate for."

Cricket, which has six million subscribers and is a subsidiary of Leap Wireless, will announce on Wednesday the introduction of a line of Android phones for $50 to $70 a month. These plans automatically include Muve, and are in addition to the Samsung, Huawei, HTC and other models on which Muve is an option. (In June, Cricket also began selling iPhones, but those do not include Muve.)

According to a study in June by the Pew Internet and American Life Project, blacks and Hispanics are some of the heaviest users of the Internet on cellphones.

Walter Piecyk, an analyst with BTIG Research, said that Muve would have difficulty holding onto customers as Cricket moves its customers from the more basic feature phones into Android and other kinds of smartphones.

"They're trying to increase the monthly bills of customers by selling them smartphones," Mr. Piecyk said. "The challenge with that is that with smartphones you've got more choices for musical services. So they're going to face increased competition with more mainstream music alternatives as they push their customers into smartphones."