It wasn't just emergency calls. Most Centurylink service around the US was down intermittently yesterday.
Makes you think twice about the cashless utopia the HN crowd imagines.
If the network is fully down, I don't see how the scenario for this business owner changes with blockchain, they'd have the exact same problem with a register that can't close an ACH: backlogged transactions that need to catch up eventually, meaning some card types are going to decline if the POS can't reach a clearing house utilized by the card vendor.
Similarly, for it to make it to the chain only 1 of those 15 confirmations has to connect to any larger network sometime in the future.