After the network is configured with VLANs and a DHCP server passing the tftp server IP address, then you can start Call Manager Express' initial setup on your router. Important: you run this setup only ONCE, just to get started. After the initial setup, you use the Cisco command line or CME GUI to configure the PBX.
Basic Network for CME
Cisco Call Manager Express runs the Skinny Call Control Protocol (SCCP) and not SIP for call setup for IP phones. It uses the Real Time Protocol (RTP) for transmitting audio. For connection to other PBXs and ISPs, it surprisingly uses the SIP protocol for call setup!
There's some minor house keeping to do that will save some headaches down the road. On your router, there should be a file named OS79XX.TXT (case sensitive), it should contain the current version of firmware that the phones should load from the tftp server. This file forces the phone to load the firmware. In my setup, the current version of firmware is "P00308000500". The content of OS79XX.TXT contains just "P00308000500" (no quotation marks). This file should be shared by the tftp server and from global configuration mode, issue the following command:
If you do a "dir" command on your router, you should see some files that start with P00308000500. Depending on the version of CME, all of the files may not be present.
Cisco Firmware Naming
Cisco uses a simple naming convention to identify which protocol the firmware is configured for. Cisco IP phones can download SCCP, SIP and MGCP firmware but CME can only work with SCCP at this time. The naming convention is:
You can migrate from one firmware protocol to another and from one version to another but sometimes there is an upgrade path that requires you to go through specific version in order. You will not be able to upgrade from version 3.3 directly to version 8.1. You may have to upgrade in steps.
From global configuration mode, issue the command telephony-service setup - this will begin the setup process. You will be prompted for various configuration options. For most choices, the defaults will suffice:
Attach Two IP Phones
Attach two Cisco IP phones to your network. I've found that the Cisco 7960 IP phone is one model that always works. It is very reliable and easy to get registered. The phones should now register and you should be able to call between them. The first Cisco IP phone should be extension 2201 and the second phone should be 2202.
The number one reason for phones not registering is faulty network configuration. Either the VLANs are not setup correctly, there's interVLAN routes missing, the switch's multiVLAN settings are incorrect or the DHCP server for one or all of the VLANs are not configured properly.
When an IP phone first boots, it doesn't know that it is connected to a multiVLAN port. It picks up a Data VLAN IP address and connects to the tftp server. When it downloads its configuration from the tftp server, it becomes aware that it is a multiVLAN port and reboots. The phone portion joins the Voice VLAN, picking up a Voice VLAN IP address. The IP phone's PC port is assigned to the Data VLAN. The network must be configured properly for this to work!
To aid in troubleshooting, on the IP phone, select the Settings button, next select Status menu and then Status Messages. Often the Status Messages will display clues indicating the problem. Another area, to look at, is the phone's network settings: it will display what the phone thinks is its tftp server, VLAN, IP address and Call Manager (router CME address). These are all clues that can be used to pinpoint problems.
Saving and Restoring Configurations Problem
A common method of saving the running-config is to copy and paste the "show run" to a text editor like Windows Notepad. Restoring it is the opposite, you copy and paste the text file into a terminal program like TeraTerm Pro while in the router's global configuration mode. This works well for small running-configs but restoring configs starts to fail once the telephony-service section becomes active.
The problem is that during a restore, the config becomes very large and the router cannot "keep up" with the data being sent to it. The terminal program sends the data faster than the router can configure itself. The result is that last portions of the telephony-service section does not get loaded.
There's two simple solutions" the first is to load your configs in two parts: network portion up to the telephony-service section first then the remaining config.
The second solution is to slow down the transmit delay setting in your terminal program. Normally they are set to a low value between 0-10 mSec. Change it to a longer delay of 35-50 mSec and you will be able to load complete configs without a problem.
That wraps it up for the inital telephony-service setup
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