Hello @Herndon100 There are a lot of factors that go into unlocking a device. Error 37 is not one of the T-Mobile error codes, so I have a few questions which will help point you in the right direction. Who told you the device was ineligible? What is the make and model of the phone? Where did you purchase the phone? Are you a T-Mobile customer?

You need to be a T-Mobile USA customer and your account and device must meet all of the SIM Unlock Policy requirements.

https://www.t-mobile.com/responsibility/consumer-info/policies/sim-unlock-policy

Are you a Tmobile customer?