Unlimited streaming music service MOG is expanding its footprint yet again with a new AT&T deal that will see its mobile application pre-installed on AT&T’s first new LTE smartphones: the Samsung Galaxy S Skyrocket and the HTC Vivid. The app will be pre-loaded onto these two AT&T 4G (LTE) phones, and customers will be able to try the service for free for a week. In addition, the company has integrated with AT&T’s billing system, so customers can pay for MOG via their regular phone bill.

This is the first carrier pre-load deal for the all-you-can-eat streaming music service which is now offering a catalog of over 13 million songs for $9.99/month on mobile. MOG is already available as a standalone iOS app, Android app, desktop app, in BMW vehicles, and on media centers, TVs and Blu-ray players, including LG and Samsung TVs, Samsung Blu-ray players, Boxee, Roku, Sonos and more. The service also recently saw a big bump in usage thanks to the Facebook integration. Over the past month, MOG reported seeing its monthly active users jump over 264%, reaching 160,000 users via its Facebook app during the month of October (source: AppData). If the growth rate continues, that could bring MOG to 2 million Facebook users by year-end, CEO David Hyman says.

Now as a pre-installed app on AT&T’s new LTE phones, the removal of the pre-registration process eliminates a big hurdle in acquiring new mobile user sign-ups. However, MOG will not disclose the current size of its user base, or how many more it expects the AT&T deal to bring, only saying that it expects the growth to be “significant.”