A T-Mobile logo is advertised on a building sign in Los Angeles, California, U.S., May 11, 2017. REUTERS/Mike Blake

By Harshita Mary Varghese

(Reuters) -T-Mobile added more than 1 million monthly bill-paying wireless subscribers to top estimates in the third quarter and raised its annual forecast, powered by a wave of customers switching from rivals during the crucial iPhone launch period.

For U.S. wireless carriers, the reported quarter is seasonally critical as Apple's latest iPhone models typically trigger a spike in upgrades and new subscriptions.

"In Q3, we hit an all-time high in our network perception amongst switchers and that's a big driver to the outperformance we're seeing," incoming CEO Srinivasan Gopalan said on Thursday.

"This has been our best iPhone performance."

T-Mobile's premium plans have helped it win a larger share of "jump-balls" in what analysts have described as a "musical chairs" environment.

The monthly-bill paying wireless subscriber additions marked T-Mobile's highest in the third quarter in more than a decade. Analysts had expected 844,900 additions, according to FactSet.

However, shares slipped about 2% in early trading after the company raised its annual capital expense forecast by $500 million to about $10 billion, driven by the inclusion of newly acquired UScellular.

SATELLITE PLAN BIG DRAW

T-Mobile is also drawing customers with its T-Satellite plan, which allows users to connect in remote or rural areas where traditional wireless service is limited.

A vast majority of users that are opting for the direct-to-cell service are getting it through T-Mobile's "Experience Beyond" plan, which offers it at no extra cost, Mike Katz, president of marketing, strategy and products, T-Mobile, told Reuters.

T-Satellite, which commercially launched in July with access limited to SMS texting, MMS, picture messaging and short audio clips, now supports widely used apps, including WhatsApp, Google Maps and X.

The carrier now expects to add between 7.2 million and 7.4 million total postpaid net customers in 2025, compared with its prior projection of 6.1 million to 6.4 million additions.

Total revenue for the third quarter came in at $21.96 billion, compared with expectations for $21.92 billion, according to data compiled by LSEG.

(Reporting by Harshita Mary Varghese in Bengaluru; Editing by Sriraj Kalluvila)