I am responsible for a branch office with 1800 IP phones. We reach the Hub-data center CUCM 8.5 via MPLS and SIP Trunking circuit (DS3). I have no backup circuit in this region except access to POTS lines.
In the event the MPLS circuit and SIP trunking goes down the hill I need to provide the hardware and pay licenses to allow survivability.
Imagine I need to spec an appliance to run CUCM 8.5 to provide a backup to get voice services.
I am considering the MCS Server 7835 (it supports up to 2500 users/Ip phones) according to Table 8-3 listed below.
In addition to the MCS server and CUCM, what type of gateway or device you guys would recommend in this scenario so that I could connect the POTS lines to? From there I believe the MCS 7835 CUCM would reach the PSTN in the event the MPLS & SIP circuit goes down.