On Fri, Aug 29, 2025 at 09:37:43PM +0000, Christoph Lauter wrote: > I made some progress debugging the issue. It is an issue with my Google Pixel > 9 and how it interacts with a sysmocom SIM card and MCC/MNC 999/70.
It sounds like this is not about how it interacts with the SIM card -- sounds like the phone is a nut for VoXxx and, after SUCCESSFULLY attaching, sees there is no VoWiFi available, and wants to try another network. I've seen similar during own tests: phones connect to circuit-switched, but my SGSN being broken caused a packet-switched failure, and the phone would rather try another operator first. One way was to switch off mobile data on the phone. Actually, yours might also be all about packet-switched. Can you disable mobile data on your phone and try again with a non-testing PLMN? Or maybe offer a working data uplink on your network, like SGSN+GGSN? It can maybe maybe also be roaming related, like, when your SIM card's start of the IMSI PLMN is the same as your cell's broadcast PLMN, maybe the phone is more eager to stay put? Anyway, your success on 001-01 suggests that it is not about SIM or network, but about a picky phone OS trying to select a fully Gooey-featured operator. > I have deactivated 5G and IMS using the scripts provided with pysim. In my testing I usually just tell the android phone's settings to use only 2G or only 3G, in the advanced settings for network & sim cards, like somewhere near the manual network selection. > When I switch the MNC/MNC on the SIM card to 001/01, I see an option on the > phone to disable Volte and Voice over Wi-Fi. When I do disable Volte and > Voice over Wi-Fi, the 2G disassociation issue goes away. (Likely, 001-01, the testing PLMN, puts the OS's baseband handling in testing mode, with less tight scrutiny on the amount of "Goo" in the network.) ~N -- - Neels Hofmeyr <nhofm...@sysmocom.de> https://www.sysmocom.de/ ======================================================================= * sysmocom - systems for mobile communications GmbH * Siemensstr. 26a * 10551 Berlin, Germany * Sitz / Registered office: Berlin, HRB 134158 B * Geschaeftsfuehrer / Managing Director: Harald Welte
