Journal

Notes from the register.

Reference pieces on how device identity actually works — written from the register's side of the problem, for the people who have to build against it.

FundamentalsWhat an IMEI actually tells youFifteen digits, three parts, one of them a checksum. What the number encodes, what it doesn't, and where people read too much into it.
FundamentalsMEID and IMEI: when you still meet the other oneTwo identifier schemes from two network families. What actually differs, and what to do when a device hands you fourteen hex characters instead of fifteen digits.
IndustryWho hands out TAC codes, and why no database is completeType Allocation Codes are issued, not discovered. How the allocation chain works, and why every TAC database — including ours — has gaps.
IndustryOne phone name, many actual devicesThe name on the box is marketing. Underneath it sit regional variants, carrier builds and separate code names — and they are not interchangeable.
ApplicationsWhere the IMEI sits in a buyback flowTrade-in and buyback operations run on device identity. A walk through the intake pipeline, and the four places a lookup earns its cost.
SecurityWhat an IMEI blacklist is, and what it is notBlacklists are network access controls, not ownership records. How they work, who honours them, and why a clean result is weaker evidence than most buyers assume.
SecurityWhat actually happens after you report a phone stolenThe chain from a police report to a blocked handset runs through several organisations. Where it works, where it stalls, and what to do in the first hour.
IndustryHow the world's phones get counted, and why the numbers disagreeShipments, connections, subscribers, installed base: four different quantities routinely quoted as one. What each actually measures.