[EdwardDiego]

Exactly. 1) is usually already catered for (for some hours, at least) with battery backups at the cell towers, and as for 2), only building capacity not needed 99.9% of the time will fix it.

During the Christchurch 2011 earthquake, the cellular services were taken down immediately by several hundred thousand people simultaenously trying to ring loved ones. Luckily the payphones were still operational to an extent - you couldn't call within Christchurch, but calling to locations outside of Christchurch worked.

It took about 8 or 9 hours for the backlog of SMS messages to be delivered on the day of the quake.