Some T-Mobile customers with older cellphone plans learned yesterday that their bills will see a $5-per-line increase beginning with their April or May bills. This comes after the company raised rates last June on other legacy plans.

T-Mobile says that if your plan falls under the "Un-contract Promise," which guarantees your rates won't increase, it will pay your final month's recurring service charge if you decide to leave (as long as you let the company know within 60 days).

T-Mobile has begun another wave of price hikes, this time hitting customers with legacy plans.