A story of telephone lines, secret connections, and the 8 channels that let helpers share secrets
With six different helpers in the M2M system, there are a lot of conversations happening at once! The EUM talks to the CI. The SM-DP talks to the SM-SR. The Operator talks to both the SM-DP and SM-SR. SGP.02 defined 8 standard interfaces (ES1–ES8) so all these channels are secure and standardised.
ES1 is the ordering line: the Fleet Owner tells the Key Factory "make me a profile for this robot." ES2 is the reporting line: the Commander sends status updates back to the Fleet Owner, like "profile installed successfully" or "robot #8721 is now on Network B." Order and report: the heartbeat of the fleet!
ES3 is the line between the Key Factory and the Commander: they ask about robot identities, send encrypted profiles for relay, and check each other's certificates. ES4 is the most critical interface: it's the secure tunnel from the Key Factory directly to the robot's vault chip, where all the secret handshake math happens!
ES5 and ES6 connect directly to the robot's ISD-R channel for local profile management. ES7 is the special handover line when Commanders change. ES8 is the chip-building line: the EUM and CI exchanging certificates when a new robot is born. Eight interfaces, six helpers, one seamless system!
The ES interfaces are the invisible plumbing of eSIM. They don't live on the chip: they're off-card, running between servers in data centres around the world. Every ES interface uses mutual TLS with certificates signed by the CI, ensuring that every conversation is authenticated end-to-end!