This is an odd problem, but a problem nonetheless. I was wondering if anyone else knows about this, if this is a firmware bug which will be fixed or not or if anyone can explain why it happens.
I have tested this on a Q2406B fw652 and a Q24PLUS fw657b.
Perform a reset (power of CFUN) with a SIM present.
Now swap the SIM by hand, each time waiting for it to register and initialise (note that 32K SIMs initialise within 3 or so seconds so they are better to test with for this).
Now, if the SIMs are on different networks, on the 41st swap the OS reboots with WIND: 3
If the SIMs are on the same network, this happens on the 61st swap.
I have tested it with an OpenAT app running and monitoring CREG and other values which then indicate that this happens on registration (which never completes) after the 41st/61st SIM insertion. The OpenAT app is never notified of registration status change or other WIND indications relating to SIM cardholder.
Without the OpenAT app running this still happens, but the WIND indications and CREG response manages to show before the reset (WIND: 3).