T-Mobile USA, the fourth largest U.S. mobile provider, said it is cutting another 900 jobs.

The cuts will come on top of the roughly 1,900 it announced earlier this year.

The unit of Deutsche Telekom is looking to preserve cash for investment in its network after its proposed $39 billion purchase by AT&T Inc failed late last year due to regulatory opposition.

T-Mobile USA, which is spending $4 billion to upgrade its network, said in March that it would close seven call centers, cutting about 5 percent of its roughly 36,000-strong workforce.

It had indicated at the time that it could cut more jobs at a future date.

The seven centers employed about 3,300 people. The company said at the time that it would offer transfers to employees of the shuttered call centers, as it planned to add 1,400 jobs at its remaining 17 centers. (Reporting By Sinead Carew; editing by Carol Bishopric)