So do cell phones automatically connect to the strongest 2G cell tower? Aren't they filtering for cell towers that only belong to their respective carrier?
The SIM includes a list of preferred and forbidden networks, but I'd guess if a non-preferred, non-forbidden network is significantly stronger than a preferred network, the phone would ask if it could connect.
Also, the fake tower could just claim to be networks that are commonly preferred.
The unlocked phones I've used can be put into auto mode (strongest signal, I guess?) or preference mode. Carrier locked phones do not switch to other providers unless there's no service. Then it'll switch over to another carrier but only allow emergency calls (911 in NA). I'm not sure what type of handshakes/communications happen in the background
2G is an open standard, and I'd imagine it's not hard to find a lecture deck about how 2G handshake and session establishment. But to briefly guide your inquiry, I recommend looking up CRO and C1/C2 criteria.
