It depends on what you mean by "voice kit" and what protocol you are running. I'll assume that it is a single voice gateway and, as such, will focus on the protocol question.
In all cases, if you are chaning the IP addressing scheme then you will need to modify the physical and logical interfaces on the router acting as a voice gateway. This should be relatively straightforward and is the same for any network infrastructure device you re-IP. Also, if you use network ACLs or firewall rules on your intra-network communications (i.e. voice network to data network) then you may need to make adjustments there as well. Again, standard fare for any network admin.
If your gateway is MGCP then you do not need to modify anything on the gateway itself (other than what has already been noted). If your gateway host name and domain is remaining unchanged then you don't need to do anything on the call manager either. If you are changing the gateway host name or domain then you need to reconfigure the gateway in CUCM (Device > Gateways). Find your old gateway name. Edit and adjust accordingly.
If your gateway is H323 then you will need to adjust the H323 bind address. Search the config for "h323-gateway voip bind ...". Adjust the address accordingly. This command will be attached to the interface (usually a loopback interface) that is associated to the IP address. If you are using BACD or other application on the voice gateway then you may need to adjust dial peers that reference any loopback (or other local interface) on the gateway. You will have to search your config for these instance. Look under voip dial peers. Don't mess with the voip dial peers that point to CUCM.
For H323 configs on CUCM, you will need to change the IP address assigned to the H323 gateway device. You can simply edit the gateway, change the IP, save and reset the gateway device.
For SIP, the same is true on the IOS-side for any apps you may be running locally on the gateway. The binding command for SIP doesn't reference the IP address (just the local interface) so you are good there. If you are doing CUBE then you will need to look at voip dial-peers as well. On the CUCM side, you will need to edit the SIP trunk, scroll down to destination, and modify the IP address (if you are using IP). If you are using DNS (A or SRV records) then you just need to modify the resource record in DNS. As with H323 gateway, if you modify the SIP trunk don't forget to reset it.
If you have CUE on the host then you'll need to change the IP on that system too. This can be done from the router CLI. Edit the IP addressing (several commands) for the service engine and then reload the engine.
More specific instruction would require more specific background.
HTH.
-Bill (http://ucguerrilla.com)
