I'm surprised I havent read from the comments how funny it is: Of course I know it wasn't a true restriction, after all its a man made program; however, isn't it convenient for years T-Mobile told customers those plans had restrictions, line caps that could not be changed, saying they couldn't make changes to the plan and you would have to switch plans to add more lines.....

Yet, they are able to raise price as it fits them... Comical and pathetic.

Self imposed limitations....

fiduciary duty requires that directors of corporations protect the interests of shareholders’ investments—including maximizing profits where reasonable and within the bounds of the law.

even if technically illegal on paper (which i’m not sure it is), so long as there is no enforcement or accountability, t-mobile and similar entities have literally no reason do do better. they are literally just holding up their end of the law.

in other words, this unfair treatment isn’t just one of many unfortunate flukes. it is literally baked into the system as a requirement.

So they had a price lock guarantee that would stop your phone lines from increasing in price. And as far as I am aware, they stuck to that. Some people thought they had that when they actually had signed up before that point. If they had ended up signing up before that point, then they were on Uncontract, which says that they will pay your last month's bill if you decide to leave.