Cisco 7905/7912 IP Phones

Basic config

The 7905/7912 series phones from Cisco use a different style of config files when configuring from TFTP. One composes the configuration file and then converts it to a binary format the phone can read. This conversion is done using the cfgfmt utility which you can find in the .zip file of your firmware image.

The filenames of the config files are gkdefault.cnf for the default settings and gk<$mac_address> for the phone-specific configuration for the 7912. For the 7905, change "gk" to "ld".

It is also possible to configure the phone from the LCD screen: for this, press the globe button, select settings, go to network or SIP settings and press **# to unlock the settings (if you don't do this, you won't be able to edit them).
If your phone asks for a password, you might want to reset it to the factory defaults. The default password (for the 7912) is 1234.

The administration guide can be found here.

Firmware and other software can be found here if you have a Cisco CCO login. Otherwise you need to buy a service contract, $8-15 a year.

Audio parameters

The default SIP software load results in an odd fault: no receive audio on many calls except if you dial a digit after the call connects. This is due to silence suppression being on by default. This can be changed in the web configuration under Audio Parameters; be sure that AudioMode is set to 0x00000010 rather than 0x00000011.

Note that the bits of the Audio Parameters also set the DTMF method used, as follows:

Bit 0: G.711 silence suppression:



Bits 1-3: Reserved.

Bits 4-5: DTMF transmission method:

–0=Always inband.

–1=Negotiated via SDP.

–2=Always out-of-band.

Bits 6-31: Reserved.


Choice of codec is set via the RxCodec and TxCodec parameters as follows:

1 = G.711A-law

2 = G.711u-law

3 = G.729a

Further details for some of the less obvious settings can be found at: on this Cisco Web page

Upgrading the software

Download the firmware package, copy the upgradecode line from the gkdefault.txt file in the package, paste it into your SIP config text file and run the cfgfmt program (cfgfmt.exe for Windows, cfgfmt.linux for Linux and dfgfmt.sun for Sun) to convert it to binary. Upload the firmware .sbin (or .zup with older 7905s) and the new gkdefault.cnf to your tftp server and reboot the phone.
A shortcut to reboot / restart Cisco 7905G phones is **#**.

Changing the logo

It is also possible to change the logo on these phones, but a different approach is needed than with the 7940/60 series.
First, one has to make a monochrome .bmp of 88 by 27 pixels and save this somewhere.
Then you have to get the bmp2logo.exe program (included in firmware release zip files or separately downloadable at

bmp2logo download

syntax: bmp2logo.exe <imageid> <infile> <outfile>

image id: a unique integer identifier for this image
infile: the input .bmp file (make sure it's monochrome and not grayscale)
outfile: the output Cisco logo file, any file extension will do

example: bmp2logo.exe 10 newlogo.bmp newlogo.logo

and then in your config txt file you have to add:

So in this case, it would be:

And naturally you have to convert this to binary again with the cfgfmt program and upload the binary config and logo file to your tftp server and you should be all set.

For those without Windows systems, Pontus Freyhult has implemented the same functionality in Python, which should run fine on most systems (does require Python Imaging Library though).

Resetting to factory defaults

Read the next section before doing this!

Step 1 Press the Menu button.

Step 2 Use the Navigation button to select Settings, and then press the Select softkey.

Step 3 Use the Navigation button to select Network Configuration, and then press the Select softkey.

Step 4 Perform either of these procedures:

Procedure A:

  • Press **2. The phone displays "Do you want to reset all system settings to default values?"

  • Press the Yes softkey.

Procedure B:

  • Press **#. If your phone displays "Enter Admin Password," enter your password and then press the Enter softkey. Make sure that an unlocked padlock icon appears in the upper-right corner of your LCD.

  • Scroll to Erase Configuration.

  • Press the Yes softkey and then press the Save softkey.

The phone cycles through normal startup procedures.

UPDATED 26.01.2016

Another yet procedure to reset Cisco 7912 (perhaps it will help if in "dhcp loop")
" * + 0 + 4th Softkey and entered 322873738# to reset the phone to factory defaults "
source found at:

Problems if no default password set

If you do set your phone back to factory defaults, it may have a blank admin password (the 'UIPassword'), in which case you can no longer change the phone's settings from the Web interface! The only way to re-setup the UIPassword is via TFTP, which means you need to have a tftp server running on your network. A very useful, free, Windows-based TFTP server can be found here: TFTPD32

In order to re-setup the UIPassword, your TFTP server must present the file gkdefault.cfg (7912) or lddefault.cfg (7905) to the phone as it boots (in fact, the parameters placed in these files are picked up by ANY 7912/7905 as they boot.) The contents of the .cfg file start out as a text file containing something similar to the following:

  1. Set the GUI/Web config password to 1234; the password must NOT be 0
  2. (disabled) if configuring via the phone's web interface is desired.


Unfortunately, the actual .cfg file is made by using a Cisco software tool to compile the text file into the desired .cfg file - and this tool is only available to users with support contracts. If you do obtain the official software kit then there is a sample .cfg containing the required text that can just be copied to your TFTP root folder.

If you do not have the ability to re-setup your UIPassword, you may want to carefully consider whether resetting your phone completely is a good idea!

Footnote: All of this hassle seems to be Cisco's way of "punishing" those who dare to use SIP on these phones!

Rebooting the phone

The phone can be reset through the keypad by scrolling into Settings, then pressing **#** and answering "yes" to the prompt "do you wish to reboot the phone?"

SIP software limitations (please add)

So far I have come by the following limitations (software 8.0.1)

  • XML services are not supported
  • US Daylight Savings Time Policy Change Effective March 2007 is not supported.
    • The problem is that the "system time" and all timestamps will be incorrect by an hour for three weeks in the spring and one week in the fall.
    • Cisco is not providing any updates to correct this problem.
    • Workaround: You will need to manually adjust TimeZone parameter. Menu >> Settings >> Network Configuration >> Time Zone Time Zone configuration.
    • See for more information

Cisco Announcement of End of Sale/End of Life for the 7905G

Cisco has recently announced that the 7905G phone will become End of Sale on 01-JUN-2006, end of software maintenance on 01-JUN-2007 and End of Support on 01-JUN-2011.

Customers are encouraged to migrate to the Cisco IP Phone 7906G when available (approximately May '06). The Cisco IP Phone 7906G will offer a greater feature set than the current Cisco IP Phone 7905G. When ready, information about the replacement product will be found at:


You may run into a problem where your 79XX phone loads the appropriate GK file or gkdefault.cfg from the TFTP server and just stops there, even though you expected it to download a new logo, firmware, etc. Make sure that your "Profile Encrypt Key" is set to "0", and not any other value. To set, go to:
Menu Key-> Settings-> Network Configuration -> Profile Encrypt Key -> Edit
(make sure your phone is unlocked by pressing **#)

Where is the convert file ?

Everyone talks about the convert file . Find it here attached . And how to use it look at the example below
Change the configs in gk00175981a234.txt where 00175981a234 should be the mac address of your phone. Make relevant changes to the text file . Once completed , from the shell run

bash# cfgfmt.linux <input> <output>

input gk00175981a234.txt
output gk00175981a234

download the convert file here

Created by: wencevdm, Last modification: Tue 26 of Jan, 2016 (23:10) by admin
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