Can i use the pop-up timer that comes with frozen turkey to gauge if it's ready to eat? i heard it's unreliable and unsafe.

We'll : It's best to use a regular cooking thermometer that shows 160°

Buy thermometer : A whole turkey is safe when cooked to a minimum internal temperature of 165 °F as measured with a food thermometer. Check the internal temperature in the innermost part of the thigh and wing and the thickest part of the breast. A meat thermometer is the sure way of knowing it's done.