T-Mobile USA will shed another 900 jobs in the midst of a massive restructuring.

T-Mobile officials said the job loss will be offset by hiring 550 new employees, primarily in the marketing sector as part of an aggressive advertising campaign, leaving a net reduction of 350 employees.

“While difficult choices had to be made, restructuring our organization will help us better respond to market and customer demands and bring opportunity for continued career development and growth for many of our employees,” T-Mobile Chief People Officer Larry Myers said in a statement.

T-Mobile would not say how many employees from the Bellevue headquarters will be subjected to layoffs, and exactly which departments will face the biggest hits. The organizational changes will not affect the technicians in engineering, customer service representatives in the 17 remaining call centers, or front-line retail employees in the company’s stores.

The mobile company, which was set to combine with AT&T before a $39 billion deal fell through, previously announced a decision to close seven of its call centers, resulting in a net loss of 1,900 jobs.

Simultaneously, the company has hired approximately 1,000 people to help prepare and strengthen T-Mobile’s 4G LTE wireless network.