T-Mobile is finally killing off Sprint SIM cards, some three years after the magenta carrier purchased its rival.

T-Mobile purchased Sprint in April 2020, creating the second-largest carrier in the US. Despite T-Mobile’s efforts to migrate Sprint customers to T-Mobile SIMs, some Sprint customers have continued to hold on to their legacy cards.

According to The T-Mo Report, T-Mobile finally forcing the issue, with May 1 as the final deadline for customers with a Sprint SIM. The company is sending out notices to customers, informing them of the deadline:

T-Mobile customers that want to continue service after May 1 will need to take action or switch to another carrier.