connieboy-13 cell tower triangulation is the easiest way to track someone. Where your number stays at night is probably your home and where it is at the day is your work location.
If you turn off your sim or enable airplane mode cell company cant track you anymore. But they still know its you and you turned on airplane mode at specific time which can be used against you.
Im using jmp.chat. ported my sim to their voip service. Got an data only sim from the them which doesn't have a phone number. Their esim are Plus mobile wich is from Poland i believe with international roaming on T-Mobile in US. They collect no identifiable information while signing up.
I enable the esim only when its really needed but most part im wifi only.
Probably T-Mobile can still see my imei, but wont be able to identify who it is. I usually turn the sim off before i reach my home.
The issue is, its not for someone who use lots calls and data bcz you get 120 minutes /month with the monthly plan and its start charging if you use more than that. (1$ is approximately 120 minutes) and data is 7$/gb but data never expires also they only support 4g as of now.