Might be only a bit related, but osmocomBB [1] is a quite complete project that implemented an open baseband library. It can be installed on a lot of old dumbp

Might be only a bit related, but osmocomBB [1] is a quite complete project that implemented an open baseband library. It can be installed on a lot of old dumbphones and allows to create a base station and mobile station. Might help you to understand the inner workings of the network protocol quirks. Back then it was known to be _the_ project to easily build an IMSI catcher, so its scene got a lot of redteamers using it. There is also an ongoing effort to reverse engineer the usb modem of the pinephone, but afaik it's still a lot of work. [2] [1] https://osmocom.org/projects/baseband https://osmocom.org/projects/baseband [2] https://github.com/Biktorgj/pinephone_modem_sdk https://github.com/Biktorgj/pinephone_modem_sdk