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Picture of FCSIM1 card front Picture of FCSIM1 card back

Anyone who operates their own GSM network typically needs to program and issue their own SIM cards — the alternative approach of letting alien SIMs onto your network in guest roaming mode with authentication and ciphering disabled is generally unattractive. And if you are a small community or lab operator, issuing your own SIMs practically means being able to obtain (buy in small quantity) what are called programmable SIMs: cards that allow you to program your own identities (IMSI, possibly ICCID too) and keys (Ki and A3+A8 algorithm selection) via some documented mechanism, typically using a special ADM PIN.

We are not the first vendor to offer programmable SIM cards — far from it. The most famous and most popular (at least in the Osmocom community from which we offshoot) brand of programmable SIM cards are those sold by Sysmocom in their webshop — and we (FreeCalypso) used them too before we had our own. However, these most common varieties of programmable SIM cards (Sysmocom and other vendors we heard of over the years) are oriented toward modern users: those who operate newer G networks beyond pure GSM, and those who are going to insert their SIMs into modern phones. From the perspective of someone who operates a pure GSM/2G network for the sole purpose of providing service to vintage mobile phones, these modern taste programmable SIMs are rather unpleasant:

Fortunately, we as in FreeCalypso were able to find an older programmable SIM card model that is GSM 11.11 SIM only, without USIM or ISIM applications (and furthermore, no UICC at all!), these cards were still freely orderable at least as of 2021 (when we got our batch), and we were able to get them made for us in a 2FF-only cut, meaning that the 2FF piece is fully solid!

The card model we got is one that was previously used and sold by Sysmocom (apparently some time around 2013), known in the Osmocom community as GrcardSIM2, made by Grcard in China. We got a new batch of these cards made for us in 2021, in a 2FF-only cut with our own color scheme and with FreeCalypso artwork on the plastic, and our version is called FreeCalypso Community SIM, model FCSIM1. We opted to not provide any programming data to Grcard factory at the time of batch production, instead our model is that every downstream user needs to program their own card(s) as needed for their unique environment using our fc-simtool utility, which is the official programming tool for FCSIM1.