This paper was published a year ago, describing a network topology that prevents IMSI-based phone tracking and now this week the authors have turned into a commercial service. This is great news for privacy by eliminating one of the unique, permanent identifiers your phone uses.
This doesn't do anything to anonymise your hardware IMEI number however, but as far as I'm aware changing that is illegal in many countries and as such software to change this is rare, possibly some Xposed modules. Still, this in itself is a groundbreaking so thought I'd share this with the rest of the forum.
P.S. I'm not affiliated with this service.