SM-SR

SM-SR (Subscription Manager Secure Routing) is the server that remotely manages an eUICC in the GSMA SGP.02 machine-to-machine (M2M) eSIM architecture. It holds the keys to the eUICC’s platform, delivers profiles prepared by an SM-DP, and executes enable, disable and delete commands on the operator’s behalf.

How SM-SR works

SGP.02 splits subscription management into two roles:

• The SM-DP (Subscription Manager Data Preparation) builds and encrypts the operator profile.
• The SM-SR owns the secure channel to the eUICC’s root security domain (ISD-R), routes the profile to it and then manages its lifecycle.

The model is push-based: the operator instructs its SM-SR, and the SM-SR contacts the device — typically waking it with an SMS and then opening a session over SMS, CAT_TP or HTTPS. The device itself makes no decisions; there is no local profile assistant and no user interaction.

The SM-SR lock-in problem

Each eUICC is linked to one SM-SR at a time, usually chosen when the eUICC is manufactured. Moving a device to a different operator means the new operator’s SM-DP must integrate with the existing SM-SR, or the eUICC must go through an SM-SR change — a multi-party procedure that needs cooperation between the old and new SM-SR operators. Across many operators and many platforms, this integration overhead made switching providers in large M2M fleets slow and costly.

SM-SR vs. eIM

	SGP.02 SM-SR	SGP.32 eIM
Delivery model	Server pushes profiles to the device	Device downloads from an SM-DP+, triggered by the eIM
Profile server	SM-DP (M2M-specific)	SM-DP+, shared with consumer eSIM
Who controls it	Typically fixed at manufacture	Whoever operates the eIM: device maker, enterprise or provider
Transport	SMS, CAT_TP, HTTPS	HTTPS, CoAP/DTLS and others

SGP.32 is not backward compatible with SGP.02, and the SM-SR has no role in it.

Why it matters for testing

Many deployed M2M fleets still run on SGP.02 and will coexist with SGP.32 devices for years. Testing an SGP.02 device means testing the SM-SR’s ability to reach it — often by SMS — and the profile switch that follows; testing an SGP.32 device means testing the eIM path instead. The guide SGP.32 vs SGP.22 vs SGP.02 compares the models side by side.