Unlimited music service Muve Music now has 1.4 million U.S. subscribers, a Cricket Wireless executive said this week at the World Mobile Congress conference in Barcelona. The executive added that Muve will expand outside the U.S. within a month, but did not name the carrier or country. A Cricket spokesperson tells Billboard an announcement of the carrier’s identity should happen within a month once the agreements are completed.

Muve Music could possibly become the world’s biggest music service within the next few years. People would not have thought such a thing when it launched in early 2011, but Muve Music has found a powerful combination of mobile access, unlimited music and integrated billing that hides the price of the music.

Muve Music is the subscription service of prepaid mobile service Cricket Wireless, which ended 2012 with approximately 5.3 million mobile subscribers, according to its 2012 annual statement. Muve Music is free with Cricket service plans for Android phones. In effect, a consumer gets unlimited music, talk, text and web for one monthly price. (Exactly how foreign mobile carriers will offer Muve Music with their wireless plans is unknown.)

Many foreign mobile carriers in other countries could be well suited for Muve Music’s business model. Pre-paid mobile plans are relatively common outside the U.S. For example, 74% of Russian smartphone owners use pre-paid mobile plans, according to Nielsen. Pre-paid use by smartphone owners is also high in Italy (66%), Brazil (55%), China (51%) and Turkey (50%). In contrast, only 15% of U.S. smartphone owners use pre-paid plans such as Cricket Wireless.

Given the prevalence of prepaid mobile services outside the U.S., Muve Music has the ability to tap into markets larger than the U.S. mobile prepaid market. Consider the numbers: in its home country, 85% of the U.S. market doesn’t even use prepaid services. But, for example, 55% of the Brazil’s 260-million mobile phone market uses pre-paid services, and 44% of the Brazilian market is smartphones.

The service must have experienced a recent growth spurt. Cricket’s annual report released last week put Muve Music’s December 31st subscriber count at 1.1 million. Muve Music announced that number on January 8. That means Muve Music added 300,000 new subscribers in roughly 8 weeks. The service had 600,000 subscribers this time last year.

This update puts Muve Music in the lead in U.S. subscribers, at least in terms of the information companies have made public. Spotify announced it had 1 million subscribers in early December. The last major milestone Rhapsody announced was 1 million subscribers in December 2011.

Other services offer mobile apps but lack Muve Music’s level of integration. Cricket created a way for consumers to acquire digital music without jumping through an additional hoop. Rhapsody offers something similar to Muve Music through its partnership with MetroPCS. A subscription to Rhapsody can be had for an extra $5 on one’s MetroPCS bill. [Billboard.biz]