T-Mobile US Inc. (NYSE: TMUS), the holding company for Deutsche Telekom (OTCPK: DTEGF) AG's various mobile communications subsidiaries outside Germany, said late Tuesday when it reported its Q1 2013 results, that from April 12 up until now, the company has sold approximately 500,000 iPhone5s to new and existing customers.

The news comes as the mobile-communications provider reported positive customer momentum throughout the quarter and the first positive branded customer growth in four years.

T-Mobile USA in March launched the Un-carrier value proposition by introducing a Simple Choice service plan and providing customers with discounted prices on popular devices.

As a result, branded customers rose by 3,000, while overall the company added 579,000 customers to its base of 34 million in the U.S. market. T-Mobile reported late Tuesday that its Q1 revenue declined 7 percent on service revenue losses while adding new customers.

The wireless carrier recorded total revenues of $4.68 billion for Q1, compared with $5.03 billion for the year-ago quarter. Service revenue decreased 9.9 percent to $4 billion but was offset by increased equipment revenue. Its adjusted earnings, excluding interest, tax, depreciation and amortization, totaled $1.2 billion, a 12.4 percent increase over Q4 of 2012 but a 7.5 percent decline over the year-ago period.