T-Mobile garnered double-digit profit growth and record revenue in the third quarter as the telecommunications firm worked to win federal approval for its $26 billion merger with Sprint.

Net income jumped 45 percent in the three months through September to $795 million, or 93 cents per share, higher than analysts' expectations. Revenue at the Bellevue, Wash.-based firm grew 8 percent to a record $10.8 billion.

T-Mobile added 1.6 million customers in the quarter, a 23 percent year-over-year increase. The company said it led the industry in signing up new users for traditional mobile plans for the 19th straight quarter, adding 774,000.

The growth was due to “investments we are making in network and in customer experience,” Chief Executive Officer John Legere said in a statement. “Despite the work under way to close the merger, we delivered our best financials ever."

The company's stock rose 2.6 percent to $65.57 in after-hours trading in New York.

T-Mobile and Sprint — the nation’s third- and fourth-largest telecommunications firms respectively — argue that a merger is necessary for them to keep competing against bigger rivals Verizon and AT&T. The companies have pledged to spend billions in developing a network for fifth-generation wireless technology, which promises wireless speeds only possible now with a hard-line connection.

While the regulatory process is not yet complete, Legere said the firm still expects the deal to close in the first three months of 2019.

"We have completed a number of major milestones and remain optimistic and confidence that once the facts are reviewed by regulators they will recognize the…pro-competitive and pro-consumer benefits of this combination," he told investors.

T-Mobile is currently building out its own 5G network and plans to release smartphones for it in 2019. The firm hopes to introduce a nationwide network by next year.