How to Convert a Cisco IP Phone to SIP

Cisco IP phones are capable of running SCCP (Skinny Call Control Protocol, also sometimes referred to as “skinny”) to function with Cisco CallManager, or Session Initiation Protocol (SIP) in order to function with popular SIP based platforms such as Asterisk or Trixbox.   By default, Cisco IP Phones ship with SCCP firmware loaded, and will need to be re-imaged with SIP firmware in order to be used with SIP based IP PBX platforms such as Asterisk.

Cisco IP Phones are designed to load different firmware versions on bootup, by administering the text-based configuration files that the phones download from a TFTP server. Want to load SIP firmware on your Cisco IP Phone? Follow along after the jump for instructions on how to do just that…

If you have recently purchased a Cisco IP Phone, and want to properly configure it for use with Asterisk, you need to do a few things in order to get your phone ready to run in a SIP environment.   For starters, you will need to register with Cisco.com online and obtain a userid and password for the Cisco website.

You will also need to purchase a valid Cisco Technical Support Service Agreement, or SMARTnet.  There are many different SMARTnet versions available for authorized Cisco resellers.  If you have a Cisco CP-7940G phone, the appropriate SMARTnet would be the CON-SNT-CP7940.  Expect to pay around $10 for your SMARTnet service agreement.

Step One:

Once you have obtained your SMARTnet service agreement and registered with Cisco, go to the Cisco firmware downloads section of the Cisco website and grab the fimware configuration files that you will need to place into the root directory of your TFTP server (If you are using a Linux machine for TFTP, the files will need to go into the tftpboot directory).

For the purposes of this tutorial, we’ll assume that you are familiar with setting up and administering a basic TFTP server.  For windows users, SolarWinds has a free TFTP server application which you can download here.

You will need to grab the following files:

P0S30100.bin—This is the Cisco SIP software image.  Be sure to download the file in binary format, in order to ensure that it is not corrupted.  Note: There are many different variations of this file, which depend on the version of SIP software that you want to load on your phone.

OS79XX.TXT—This file tells your Cisco IP Phone which binary it needs to download from your TFTP server.  Note that this file is case sensitive and it must only contain the name of the file that you want to load, without the .bin extension.  For example, if you attempt to load the SIP version 2.3 software, it must contain only the line P0S30203.  If you attempt to load versions 3.0 and later, the file name must be in the format P0S3-xx-y-zz.  Following the same naming convention, if you try to load the SIP version 7.1 software, OS79XX.TXT must contain the line P0S3-07-1-00.  The binary referenced here must also be present in your TFTP root directory.  Without this file, your Cisco IP phone won’t  know which file it needs to retrieve, in order to replace its existing software.

SIPDefaultGeneric.cnf—This is an example configuration file which contains configuration information and setting variables relevant to all Cisco IP phones.

SIPConfigGeneric.cnf—This file is similar to the previous one, except that it contains information relevant to a specific phone instead of to all phones.

RINGLIST.DAT—This file contains a list of audio files which are the custom ring type options for the Cisco IP phones.  The audio files listed in RINGLIST.DAT must also be in the root directory of your TFTP server.

ringer1.pcm—This file is a sample ring tone that is used by the Cisco CP-7940G IP Phone.

Step Two:

With a text editor (Notepad works fine), rename the file SIPDefaultGeneric.cnf to SIPDefault.cnf (used for global parameters on all phones).

Step Three:

With a text editor, rename the file SIPConfigGeneric.cnf to SIPmac_address.cnf, for each phone (for example, SIP002094D245CB.cnf).  Note: Here the MAC address of the Cisco IP phone must be specified in capital letters and the extension (.cnf) must be in lower case.  The MAC address of the Cisco IP phone can be found on the sticker that is located on the bottom of the phone, or it can be found through the phone LCD screen (choose Settings > Network Configuration > MAC Address).  Also Note: You will need to allow read and write file permissions on your TFTP server for those files… On Linux TFTP servers, issue the command chmod 777 file_name, on windows-based servers, refer to the software documentation.

Step Four:

Reset your Cisco IP phone by unplugging the power cord (or network ethernet cable if you are using PoE).  You will need make sure that your Cisco IP phone can find your TFTP server.  You will need to manually configure the phone’s IP address, gateway address, and TFTP server address.

• Press the following button sequence on your Cisco IP phone in order to unlock the phone: *,*,# .  By pressing (star, star, pound) on your phone you will either lock or unlock the phone, based on the current state.)
• Press Settings.
• Press the down arrow in order to select Network Configuration and press the Select softkey.  There is an unlocked padlock icon in the upper right portion of Cisco IP phone’s your LCD screen.
• Use the toggle button and the arrow keys in order to modify any parameters.  Note: When you enter IP addresses, the * key is used for decimal points.
• Press the Save softkey in order to save your changes.
• Note: In order to lock the phone settings, press **#.

If you have followed the procedure exactly as described, made sure the necessary files are in your TFTP server, and have configured your Cisco IP phone’s network properties correctly so that it can access your TFTP server, your Cisco IP phone will download and install the SIP firmware and you can now use your Cisco IP phone with popular SIP based platforms such as Asterisk!