I have a small office, 40 phones. I plan on using a Cisco 2851 Integrated Services router, running both Call Manager Express and Unity Express. It will also provide PSTN gateway services with 8-16 port FXO cards.
1) is there an industry standard for phone-to-pots line ratio?
2) is there a Hot Standby protocol for a redundant POTS gateway (Cisco 2851)?