Each type of IP phone requires firmware to register and function properly with Cisco CME. The version of the firmware depends on the type of phone and version of Cisco CME you are using. The firmware should be placed on a TFTP server accessible to the router and should be copied to the Cisco CME router. Also, the telephony-service configuration should have the firmware specified for each type of phone connected to the Cisco CME system.
The configuration shown in Example 4.2 lists the firmware for the Cisco 7940G, 7960G, and 7905G IP Phones. These files change depending on the version of Cisco CME you're using. Check Cisco.com for the correct version of these files for your system. The files in Example 4.2 are shown to illustrate where they are configured.
Example 4.3. Phone Firmware
Router#show running-config telephony-service max-dn 10 max-ephone 10 ip source address 10.0.0.1 port 2000 load 7940-60 P00303020214 load 7914 S00103020002.bin load 7905 CP79050101SCCP030530B31.zup
All the phones come with factory default firmware installed. During the registration process, the phone compares its current firmware with the load configured under telephony services, as shown in Example 4.2. If the configured firmware and the current firmware match, the phone continues with the registration process. If the firmware is different from what is configured, the phone tries to download the new firmware from Cisco CME.
It is necessary to have the right version of phone firmware for the version of Cisco CME you are using to have all the features working as designed.
In certain cases, a firmware upgrade or downgrade is not a one-step process. Also, in certain cases, you cannot downgrade the phone firmware to a lower version. For example, you cannot downgrade the firmware on a Cisco 7960G IP Phone from a signed load to an unsigned load. This process is covered in much more detail in Chapter 16.
Resetting and Restarting the Phones