T-Mobile US shifted a little more weight onto the shoulders of COO Mike Sievert (pictured, second from left), as the operator’s board of directors appointed him company president.

The title was previously held by John Legere, who remains CEO.

T-Mobile in April said Sievert would take on the role of president and COO following the close of the operator’s proposed merger with Sprint. However, an SEC filing revealing the appointment showed Sievert received a pay rise to reflect his role as president and COO the same month, in an apparent acceleration of the plan.

The promotion is the second for Sievert this year, after being named to T-Mobile’s board of directors in February. At the time, T-Mobile recognised him as one of the architects behind its Uncarrier strategy and Legere hailed him as “instrumental” to the operator’s success.

T-Mobile has not made any public comment about whether Sievert’s conspicuous rise is meant to position him as a potential successor to Legere, who has served as CEO since 2012.

Sievert joined T-Mobile in November 2012, serving as EVP and CMO before being promoted to COO in February 2015. Prior to T-Mobile, he held executive positions at AT&T, Microsoft and Clearwire.