T-Mobile says technical problems in its automatic plan migration removed free-line discounts from some customer accounts, turning what was already an unpopular rate-plan cleanup into a billing mess for longtime subscribers.
The carrier told Ars Technica that the affected accounts represent a “very small number” of customers and that the free-line promotions were not supposed to disappear. According to T-Mobile, some discounts were delayed or failed to show correctly after customers were moved to newer plans. The company said it is restoring the discounts, backdating them when needed, and reprocessing affected accounts.
For customers who built their accounts around T-Mobile’s older promotions, that distinction is not academic. A line that used to cost nothing can become a full-price line if the billing system drops the associated credit. Several customers said online that the migration produced bills far above what they had been paying.
Free lines fell out of some migrated accounts
T-Mobile has been retiring older wireless plans and moving customers to newer plans that it says are broadly comparable in price and features. The company previously told media outlets that some customers would see no bill change, while others would see a modest increase. T-Mobile also said customers moved to new plans would keep their existing benefits.
Complaints on Reddit and reporting by The Mobile Report indicate that promise did not hold for every account. The Mobile Report said it heard from users whose free-line promotions did not carry over to the new plans. It also reported that some customers saw an unexplained hotspot data add-on appear on their plans, adding as much as $15 to a monthly bill.
Free-line promotions have been a recurring T-Mobile retention tool. In one March 2025 offer reported by The Mobile Report, customers with active accounts for at least 10 years could add a free line if they already had at least two paid lines.
One Reddit user said they previously had three paid lines and six free lines for about $50 a month. After being moved to T-Mobile’s Experience Signature plan, the user said the first new bill was above $300 and did not show the free-line credits. Another user said losing free-line promotions raised the bill by $200. A third said T-Mobile support could not restore a free line that the representative described as ineligible under the new plan, offering a year of credits instead.
T-Mobile is also checking Hulu charges
T-Mobile acknowledged another migration-related billing problem involving Hulu. The company told Ars Technica that it is investigating reports that some customers were incorrectly billed for Hulu after the move and said it is working to identify the cause.
The plan migration is part of a back-end cleanup. T-Mobile chief operating officer Jon Freier told employees in a leaked email reported by The Mobile Report that the company is removing about 1,100 old billing codes. Freier said nearly half of affected customers would see no price change, while others would see increases of up to $6 per line. He also said customers would receive more premium data, more high-speed hotspot data, better international coverage, and a five-year price guarantee.
Fierce Network reported that reducing those codes would leave T-Mobile with fewer than 100, which should make it easier for the company to support features across its systems. Billing codes are not the same as consumer-facing rate plans. They tell the carrier’s systems what a given account can use, which is exactly the kind of plumbing that breaks loudly when a migration misses an old promotion.
The dispute lands after T-Mobile’s 2024 decision to raise prices for customers who had signed up under promotions marketed as having prices that would not change. Customers filed complaints with the Federal Communications Commission and a class-action lawsuit, which remains pending while T-Mobile seeks to push the plaintiffs into arbitration.
T-Mobile says the missing free lines are errors and will be fixed. The broader migration, including increases of up to $6 per line for some older-plan customers, remains in place.
This story draws on original reporting from Ars Technica.
