What is the difference between a Cisco Phone's Config File and its Firmware?

[TariqMK]

As far as I can make out, the firmware is quite simply the software it runs, pretty much like any device nowadays. However I cant put my finger on what exactly the purpose of the Config File is.

Is anyone able to help me clarify this concept?

[Georgios Fotiadis · Accepted solution]

You are correct, the firmware is the software the phone runs. The configuration file has all the settings needed by the IP phone to operate with a specific IP PBX.

[TariqMK]

Great, thank you.

Seeing as this is the case, when a phone boots up and receives Option 150 from the DHCP Server, it has the addresses of the Call Manager (TFTP Server).

Does it now pull the Config File? What about the Firmware?

My understanding is that the Phone has Firmware pre-loaded from the factory which it will use unless the Config File specifies otherwise.

If the Config File does specify for the Phone to use other Firmware, then the Phone will pull this from the same TFTP server.

Is this correct?

Lastly, what sort of information does the Config File hold exactly?

[Georgios Fotiadis]

You are correct about the firmware upgrade decision.

Some of the info it contains is CUCM IP address, date/time settings, firmware version, language, XML service URLs etc...

[TariqMK]

Brilliant, just the information/confirmation I was looking for - thank you!