What PMI actually is
Private Mortgage Insurance protects the lender, not you, when your loan-to-value is above 80 percent at origination. It shows up as an extra monthly cost until you cross certain equity thresholds defined by federal rules and your loan documents.
When you may be eligible to remove it
For most conventional loans, you can typically request PMI removal once your loan reaches 80 percent of the original property value based on your payment schedule, or earlier if a new appraisal supports enough equity. Automatic termination generally happens at 78 percent based on original value. Rules vary by loan type and servicer.
Why the servicer probably won't call you
Servicers are not in the business of reducing your payment. If you don't ask, PMI can sit on your statement well past the point you were eligible to request removal. This is one of the milestones I track for clients as part of Mortgage Under Management.