Multi-IMSI, eSIM and eUICC, acronymic heaven or hell?

There is some confusion in the market at the moment when someone asks for an eSIM.

Guest author

March 27, 2020

2 Min Read
eSIM card periodically invites expert third parties to share their views on the industry’s most pressing issues. In this article Douglas Gilmour, Managing Director at Mobius Networks, demystifies some key questions surrounding eSIM technology, and what this means for the consumer.

There is some confusion in the market at the moment when someone asks for an eSIM. This usually means an embedded subscriber identification module (SIM)- a semiconductor chip soldered direct to the PCB, rather than the usual form factor we are all use to. But if it’s soldered to the board how can the end customer choose their network?

An embedded Universal Integrated Circuit Card (eUICC), also confusingly called an eSIM, may be the answer. This standard means that you can pick your Operator and roll out across the world. When the device wakes up you can load a local network international mobile subscriber identity (IMSI) onto your product and never have to worry about roaming charges since you are always local.

Another big advantage of eUICC is that if you decide to change Operator after your initial contract has run out you can then lift the whole estate to another network with all the negotiating power that brings. The downside is with flexibility comes complication and some additional cost.

Multi-IMSI is sometimes seen as a halfway house. You can load multiple IMSIs onto a SIM so that you can take advantage of Roaming in areas where coverage is thin. You can load local IMSIs if there is heavy lifting to be done. Effectively it turns the SIM into a least cost routing option. So it looks like eUICC without the additional costs.

But whereas with an eUICC SIM you shift the SIM from one network’s HLR to another, with multi-IMSI the fundamental relationship stays with the original provider. So if you fall out with them whatever reason the only way to change the estate is to change the SIM. Which in most IoT and M2M applications may not be possible.

With all of these acronymic options you may not know if you have made the right choice until you are three years down the line. By which point it may be too late.


This article is produced in the lead up to MVNOs World Congress 2020, Where Douglas Gilmour will be speaking. Read the full article here.

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