Private LTE and 5G networks run on SIM cards, the same small chips that sit inside a phone, and more operators now program those cards themselves. A wireless internet provider, a CBRS network or a test lab can buy a SIM writer and a stack of blank cards, and then every card needs four values written onto it: an IMSI that names it on the network, an ICCID that serves as its serial number, and two secret keys called the Ki and the OPc. The network’s core has to hold the very same keys, or the card will never connect.
I built the SIM Card Generator at The Edge Mile to make those values for up to 10,000 cards at a time, in about a second. It hands back a file for the SIM writer and a script that loads the same batch into an Open5GS or Rapid5GS core with one command. Open5GS has no built-in importer for a batch like that, and Rapid5GS leaves out the command-line tool that would otherwise do the job, so the script fills a real gap. Each SIM can carry up to four APNs, the network names a device connects through, along with a speed cap, and there are presets for the network codes private operators actually use, including the shared code for CBRS networks in the United States.
Secret keys deserve care, so the tool is built for nobody to take its safety on faith. It runs in a walled-off frame that the browser forbids from sending anything over the network, so the keys are made on the operator’s own computer, never reach a server, and stay out of reach of everything else on the page. It checks its own math against the published 3GPP test values every time it loads and refuses to run if a check fails. It can also be downloaded as one file and run on a computer with no network at all.
The page around the tool teaches the rest of the job: how to program the cards, which network code to choose, and how to read the core’s log when a new SIM will not connect. The thinking behind it is in A Key for Every SIM.
If your company is bringing SIMs in-house or standing up a private LTE network, bring me in. The Edge Mile sells the Nokia CBRS kits and Rapid5GS Pro that networks like these are built on, and we run wireless networks ourselves, so we can help you get yours on the air. Write to The Edge Mile and tell us what you are building.