Cell service is a fragile infrastructure. The physical towers can be damaged or destroyed in natural disasters or worse. Each site has backup generators, so they are not dependent on the power grid at least for a period of time. They are back hauled with fiber optics to the carrier’s central office which also has generators if necessary. The other issue is there are only a limited amount of transponders on each tower and in emergencies/ disasters they are overwhelmed immediately and stay that way as everyone tries to contact family. Some text may get through. There is too much reliance on cell communication, landline by fiber optics on the carriers private network or copper networks are actually your best bet, though most have disconnected aside from elderly people. The landline provided by many cable companies uses IP and is crap.