Starting today, T-Mobile will begin migrating existing customers to higher-cost plans unless the customer contacts the carrier to opt out.
Clark.com has a story about this at T-Mobile’s Forced Plan Migration: How To Opt Out.
One line in the story talks about switching to “a cheaper cell phone service provider that runs on the same network.” However, beware that an MVNO does not provide the same coverage or quality as the provider that owns the network, and this is especially an issue with T-Mobile MVNOs like Mint or Tello. This is for two reasons. First, the MVNOs rarely provide any off-network roaming so the coverage is much less in rural areas (like all of Alaska!). Second, the MVNOs usually provide a lower priority level (QCI). There are exceptions, such as Google Voice and Consumer Cellular which do provide some off-network roaming, but neither of those MVNOs is competitively priced.