SIM Application toolkit commands

Ronald Franks ron at
Tue May 16 02:43:19 UTC 2023

The method Mr. Lad mentions allows the user/UE to trigger switching to the
"next IMSI" in the default list. The applet on the SIM also triggers its
own change based upon information in the Envelope Event Download Location
Status or Proactive Command Provide Local Information. In either of these
events, if "Normal Service" is reported, the applet will look at the MCC of
the roaming network and determine if there is an IMSI designated for use in
that country. The applet will then change EF_IMSI and send a REFRESH of the
type SIM Initialization and Full File Change Notification to the terminal
to tell it to come back in and refresh everything the modem knows about the
SIM. When this REFRESH happens that is when you see the +URC on the quectel
modems I mentioned previously via the terminal.

On Tue, May 9, 2023 at 8:36 PM Amol Lad <Amol.Lad at> wrote:

> >> The Twilio Super SIM will send a Proactive Command NAA Initialization
> and Full File Change Notification to the terminal on the IMSI change. Some
> modems, like the Quectel BG95 or EC25 will send a URC if
> >> +QUSIM: 1
> >> if it is a USIM and
> >> +QUSIM: 0
> >> if it's a regular SIM
> >> no idea about other modems however.
> >>
> > You mean the +QUSIM URC is sent to the host whenever the Full File
> > Change Notification is received by the terminal on the IMSI change?
> > i.e. no need to STK supported by the host in this case, right?
> >> I can arrange to get you a SIM for testing if needed as this is an area
> I'm interested in as well. I can also provide a SIMtrace2 pcap (or raw
> APDUs if preferred) capture of the communications between the terminal and
> the SIM if that would be helpful.
> >>
> > How do you instruct the SIM to switch IMSI?
> One way is mentioned here:
> --
> Aleksander
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