Unless you can make the calls in a pattern that suggests a different centre than the reality? (I'm interested in this because I have to solve a similar problem in my WIP.)
Keep in mind, the key feature of what I said is using a different phone (NOT moving a sim card, but the whole phone) after each and every use. Here's the biggest problem--and why I mention using paper mail and a relay--it becomes so ridiculous in a very short time it's not worth the effort.
Any phone you use could very well be intercepted by a random imsi-catcher which LE and governments are now using along with criminal elements. An imsi-catcher will trick the phone into believing it is receiving an answer back from a cell tower, and in the process download hacking software which allows gps tracking, the microphones (there is an array of them in smart phones) and cameras to be turned on at will, sonic distancing to map rooms, text/email hacking...etc. >>>>know this, they do NOT focus on finding 'a phone,' but do it to ALL phones<<<< Add to that, any information you have stored, gps routes (not that you saved, but all), wifi connections available locations, automotive systems and computers it communicates with, etc., are all retrieved.
For governments and LE, imsi-catchers are now even outdated. Think about it...in this time of Covid-19, without consent (though they laughably offer for you to download the app), they're performing contact tracing using people's phones.
Right this second in Hong Kong people are deleting social media accounts to try and erase their digital footprint...it won't help them. Their phone which they're keeping is what's compromised, PRC has already acknowledged that, and if you think due to a higher social morality or legal civil liberties any other nation isn't doing that, you'd be wrong. Those laws just mean they won't openly admit it, but will use that tech to track people down and then claim it was good detective work.
Ever notice how every modern car you get into wants to establish a connection to a new phone in the vehicle? Well, it's just been identified, and that information is transferable through the automobiles wifi and other external communication systems. Meaning, you take odd cab to X place and once there you make the call...take new cab back to where-ever...and if they put out an APB the PCs in all the police cars as they tap into passing vehicles systems can then say 'Y phone (previously identified during your call) is in Z car heading N/S/E/W along whatever street.
A PC is just as bad, and government and LE agencies have worked very hard to learn all the back routes and methods to disguise who you are and where you're located and hack into what you're doing.
Also, don't forget that just 'carrying' a credit card or other chipped identification makes you susceptible to RFID/NFC/GT that permits close range Radio Frequency IDentification, Near Field Communication, Geospatial Tracking due to those countless systems (gas pumps, stores, etc all communicating back to central systems). So all digital financial and modern identification needs to be discarded. You don't have to 'tap it' for it to work.
Point being if you're serious...
ditch the electronic stuff and all I.D.. If you're super-serious, break off all contact. Any person you have previously interacted with will become their target to snag you--IF they want you bad enough. That's what most people don't realize, they're just not that important for LE to try that hard.
Anywho... *puts on tinfoil hat*
K2
