T-Mobile says plan migration wrongly removed some free-line credits

T-Mobile said it is restoring free-line discounts that disappeared from some customer accounts during its automatic transfer of subscribers from older wireless plans to newer ones. The error landed inside a broader plan retirement program that is already raising prices for some longtime customers by as much as $6 per line per month.

The company told Ars Technica that technical issues affected a “very small number” of customers and that some free-line promotions did not appear after the migration because of a delay in applying promotional discounts. T-Mobile said those lines are still supposed to be free, and that it is restoring the credits, backdating them where necessary and reprocessing affected accounts.

T-Mobile did not disclose how many subscribers were affected, how many lines lost promotional credits, or how long customers may have to wait for corrected bills. The carrier also acknowledged a separate issue involving some customers being billed for Hulu after their migration, saying it is still looking for the cause.

Billing cleanup meets customer price hikes

The free-line problem follows T-Mobile’s recent decision to retire older plans and move customers onto newer rate plans. The company previously told media outlets that some customers would see no monthly bill change, while others would see a “modest adjustment,” and said customers moved to new plans would keep current benefits while receiving service and network improvements.

Customer complaints posted on Reddit and reported by The Mobile Report indicate that did not happen consistently. Some users said free lines accumulated through past promotions no longer appeared on their bills after the switch. One Reddit user said an account that previously had three paid lines and six free lines for roughly $50 per month showed a bill above $300 after moving to T-Mobile’s Experience Signature plan. Another user reported a $200 increase after losing free-line credits.

The Mobile Report also said some customers saw an unexplained hotspot data add-on attached to their new plans, adding up to $15 per month. T-Mobile’s statement to Ars addressed free-line credits and Hulu billing, but did not provide a detailed explanation for every reported add-on issue.

T-Mobile has used free-line offers for years to retain and expand accounts. In one March 2025 promotion reported by The Mobile Report, customers with at least 10 years of service and at least two paid lines could add another line at no added charge.

Fewer billing codes, more execution risk

The operational goal behind the plan changes is backend simplification. T-Mobile COO Jon Freier told employees in a leaked email reported by The Mobile Report that the company is removing about 1,100 legacy billing codes as it retires old plans. Freier said nearly half of affected customers would see no price change, while others would see increases of up to $6 per line.

Freier also said older 3G- and 4G-era plans carried tighter limits on smartphone data, hotspot use, roaming and video quality, and that migrated customers would receive more premium data, more high-speed hotspot data, better international coverage and a five-year price guarantee.

Fierce Network reported that eliminating the 1,100 codes would leave T-Mobile with fewer than 100 billing codes, reducing the compatibility work required when the carrier adds features to its website or app. The free-line issue shows the tradeoff: simplifying old telecom billing stacks can expose edge cases created by years of promotions.

The dispute also lands against a prior customer-relations problem. In 2024, T-Mobile raised prices for some customers who had signed up under promotions marketed as lifetime price locks. Customers filed complaints with the Federal Communications Commission and a class-action lawsuit, which remains pending while T-Mobile seeks to move plaintiffs into arbitration, according to court records cited by Ars Technica.

T-Mobile says the missing free-line discounts were mistakes and will be corrected. The company has not said it will reverse the separate plan-related price increases for customers whose bills are rising by up to $6 per line.

This story draws on original reporting from Ars Technica.