2851 PSTN gateway Hot Standby?

[v-yelmene]

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)?

[paolo bevilacqua]

You cannot really suggest a ratio without knowing the purpose of the client installation.. Thus said a reasonable ratio could be 8 to 1.

Newer CME support redundancy so using with two routers your are safe.