I really can't speak to the telecom networks, but most merchants today....
To Mike's earlier point, the days of imprinters have long gone. Most merchants have electronic terminals. If they have an issue with their terminal and it breaks, as they do from time to time, then yes, they have to contact their acquirer, financial institution, or whoever is providing the terminal for them and get it resolved. Certainly it's usually fixed quite quickly, because the retailer wants to get back up and running as quickly as possible. There's typically no backup to an imprinter, or creating paper sales drafts any more. Those days are kind of gone.
As you may recall, when we had the power blackout several years ago, a lot of merchants were effectively off the air as far as card acceptance, because the terminals need electricity.
Was there a question about phones?