You don't know this. Stop making assumptions about anything except "there will be zombies".
considering that the only power plants still active will probably be hydroelectric, solar, and maybe nuclear, i'd say it's a safe bet that in a total civilization breakdown there won't be any power for servers, phone towers, etc.
however, satellite phones will still work.
From the stuff I have right now-My colt python .357 magnum, my machete, backback full of food, water and medical supplies, hammer, nails, gasoline, matches, a saw of some sort that I would find in my messy garage. Oh, and my dad's 12-gauge powerful flashlight, crowbar.
If I could choose: M249 SAW, My dad's 12 gauge(he built it himself, its REALLY loving powerful), my machete, gas, matches, buzzsaw, backback full of food, water, medical supplies, a Hummer, planks of wood in the trunk of the Hummer, hammer, nails, one of those big flashlights that you buy at home depot, crowbar. Extra food and ammo and other stuff in Hummer too.
on the run from hordes of zombies
fancy gun runs out of ammo
big truck runs out of gas
