As for land lines - I'll never be without one. Most people don't realize that during an emergency or natural disaster, the Emergency Response Units take over ALL the wireless networks (bandwidth) for their use. Civilian use is blocked entirely. I found this out the hard way many years ago during a tornado.
That is true, but with smartphones it is of little consequence if you are near a WiFi ap. Basically a lot of providers have a wifi calling service and if yours doesn't you can get a VOIP app to make calls with. I have an old android phone with zero service enabled (in fact not even a SIM card installed) but I can make phone calls over WiFi. And if the internet goes out in all likelihood most of the landlines will be out along with the whole area being in a SHTF scenario.