T-Mobile US, which acquired MetroPCS in May, is set to double its new unit’s footprint by launching the budget brand in 15 additional markets.

The fourth largest mobile operator in the US said at the time of the takeover that its strategy is to maintain both brands but move to a common infrastructure.

MetroPCS is being positioned as T-Mobile’s prepaid brand, particularly in urban areas. Among the new markets where it will be launched are Baltimore, Houston, Memphis, San Diego and Washington DC.

Consumers in these new markets will use T-Mobile’s WCDMA/LTE network and although MetroPCS still sells CDMA handsets in its 15 existing markets, the plan is to gradually phase them out. T-Mobile is eager to refarm MetroPCS’s frequencies for LTE.

Thirteen of the fifteen new markets will be in areas where prepaid rival Leap Wireless, itself just acquired by AT&T, offers its own services.

In addition, T-Mobile has its own GoSmart brand which also targets the prepaid market.

As part of the same announcement, MetroPCS said it will offer a new tariff called “$40, period” with unlimited voice, text and 500 MB of data on a nationwide basis. It is also expanding its existing Bring Your own Phone programme to the new markets.

Subscribers in the 15 additional markets will have a choice of handsets including LTE models such as the Galaxy S 4, LG Optimus L9 and Samsung Galaxy Exhibit.

The operator will also offer, in select markets, the Nokia Lumia 521, which is MetroPCS’s first Windows Phone device, and the LG Optimus F3.