The SS7 flaws that allows hackers to snoop on your calls and SMS Locate. Track. Manipulate SS7: Locate. Track. Manipulate remote-controlled tracking device pocket.

 https://blog.3g4g.co.uk/2014/12/the-ss7-flaws-that-allows-hackers-to.html

https://www.scribd.com/document/359370710/31c3-ss7-locate-track-manipulate-pdf 

https://www.google.com/url?sa=i&url=https%3A%2F%2Fdl.ifip.org%2Fdb%2Fconf%2Fnetworking%2Fnetworking2016%2F1570236202.pdf&psig=AOvVaw2F8xomw7cNu_gxAAFPwjPo&ust=1668146898141000&source=images&cd=vfe&ved=0CBEQjhxqFwoTCPDZisz5ovsCFQAAAAAdAAAAABAO

 https://www.researchgate.net/publication/323248468_GUTI_Reallocation_Demystified_Cellular_Location_Tracking_with_Changing_Temporary_Identifier