T-Mobile US retail employees and technicians sought assurances from Deutsche Telekom that their jobs and salary will be safe if the wireless carrier is allowed to merge with Sprint, Reuters reported.

T-Mobile US, a Deutsche Telekom subsidiary, has employed approximately 52,000 full-time and part-time employees in 2018. Sprint, a SoftBank-owned telecom business in the US, had approximately 28,500 employees in 2018.

T-Mobile United, with about 500 members and backed by the Communication Workers of America and the German union ver.di, has urged Deutsche Telekom CEO Tim Hoettges to make solid and verifiable assurances that jobs will be safe, paychecks will not shrink and management will not interfere in union activities.

T-Mobile United delivered a letter late Tuesday for Deutsche Telekom CEO Tim Hoettges and the letter was given to a board member meeting with union members in Seattle late Tuesday.

Earlier, Communications Workers of America union said the proposed merger would hurt wages and destroy as many as 30,000 jobs.

T-Mobile earlier said it would need 11,000 new employees by 2024 and pledged to compete hard on building 5G network.

T-Mobile’s deal to buy Sprint for $26 billion faces a court challenge from 15 states and the District of Columbia who argue that the planned merger will mean higher prices for consumers. The trial is set for December 9.

The Justice Department has signed off on the merger while the Federal Communications Commission (FCC) has indicated it plans to approve it with several conditions including divestment.

The deal to combine the No. 3 and No. 4 U.S. wireless carriers, struck in April, was approved by both companies’ shareholders in October and received national security clearance.

T-Mobile CEO John Legere pledged to create 5G without using networking equipment from Huawei or ZTE, two Chinese telecommunications giants distrusted by U.S. national security experts.