“T‑Mobile will never change the price you pay for your T‑Mobile ONE plan.” That was the promise. The Un-contract. The whole reason millions of customers picked the magenta team over Verizon and AT&T in the first place. Now T-Mobile is retiring legacy 3G and 4G-era plans — Magenta, ONE, Simple Choice — and automatically moving customers onto “modern” 5G plans at higher monthly costs. Billing changes hit mid-July for the current wave. The company that swore it would never surprise you with a rate hike just sent the notification.
Your Bill Is Going Up More Than $4
The official per-line average understates what many legacy customers are actually absorbing.
T-Mobile frames the current migration as an average $4-per-line adjustment, according to CNET. That sounds modest until you stack it on the $5-per-line hike that already hit many legacy smartphone plans back in April 2025. PhoneArena reports some customers on older grandfathered plans face total increases approaching 60% compared to their original rates. Meanwhile, administrative fees for voice lines climbed from $3.99 to $4.49 per month — raised twice within a single year, according to tmo.report — with mobile internet line fees moving from $1.60 to $2.10. Those fees sit conveniently outside the new five-year price guarantee on talk, text, and data.
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