The issue isn't really that DHCP is hosted by the Centrex. The issue is that if connectivity between the IP phone and Centrex is lost, where would the IP phone register? But if you can get L3 connectivity to continue to Centrex when the L2 switch goes down by providing alternate paths, the phones should probably be okay. You can probably ask in the switching forum if you want more details on L2 redundancy best practices and that sort. From a voice perspective, you just need to be concerned about maintaining L3 connectivity through to your provider during a failing state. Treat it as you would any other device.
Because these aren't Cisco IP phones, I don't know how they do call preservation/survivability during an outage from the call agent/registrar.
In the Cisco world, if Cisco phones lost connectivity to the head end, they'd use SRST and register to a local device running SRST. If your phones are running SIP and can take an alternate IP for registration, you can maybe look into SIP SRST at the local site for this.
SIP traces provide key information in troubleshooting SIP Trunks, SIP
endpoints and other SIP related issues. Even though these traces are in
clear text, these texts can be gibberish unless you understand fully
what they mean. This document attempts to br...
Please find the attached HTML document, download and open it on your PC.
This provides an easy to use form where you simply answer a few
questions and it will render the proper jabber-config.xml file for you
to copy/paste. There is built in logic to verif...
CUCM Database Replication is an area in which Cisco customers and
partners have asked for more in-depth training in being able to properly
assess a replication problem and potentially resolve an issue without
involving TAC. This document discusses the bas...