13 thoughts on - Cisco IP Phones and Skinny in asterisk

  • Bilal,

    I suggest you turn on logging on your tftp server to see what files are actually being requested, and if the the tftp server is dishing them out… Try adding a few v’s to your tftp setup:

    File: /etc/xinetd.d/tftp
    Line to change: server_args = -s /tftpboot -v -v -v

    Look in /var/log/messages for the output.

    Also, I believe your 7942G has a console/aux port which is a serial port, you can learn what is happening as the phone boots up with that too.

    Good Luck!


  • I also had trouble w/ these phones at first. There was a DHCP option (?81?) you’ll have to google it.
    The phones would not talk to tftp until I set dhcp option.
    The console aux cable is easy to build and VERY useful

    Sent from my iPhone

  • Dears;

    OK, I start beleive that the problem in the TFTP and the files that I placed there.

    Now, I am using the Phone as skinny, and the files that are placed in the directory /var/lib/tftpboot/ as following:


    Well, actually the CTLSEPB8BEBF22AB62.tlv is totally empty, so should I place any thing in it? Anyone has a format for the file CTLSEPB8BEBF22AB62.tlv?

    Also, what do I miss other files that the Phone needs it?

    From the other side, what should do about the chown and the chmod for the directory tftpboot?

    Appreciate the kindly help and advise.

  • Cisco has changed the file name format a few times, so
    you may want to copy xmlDefault.CNF.XML to XMLDefault.cnf.xml

    The more important steps is how have you configured the phone
    to locate the TFTP server? Are you using option 150 in DHCP, or
    manually setting the TFTP server address on the phone.

    Technically you do not need a TFTP server, since the Skinny phones
    will try to use the TFTP server address for registration, so you
    can just set that address to point to your asterisk server. A TFTP
    server is needed if you want custom ringtones or to manage software

    For small setups or my home, I skipped setting up the TFTP server
    until I wanted to update the phone firmware.


  • Dear Stefan;

    First of all, I tried skinny and I faced two major problems (so if I am going to face same problems in sccp then no need to use sccp, so please advise).

    The two problems that I faced them are:

    1) When I do reload then the skinny channel is reloaded and that will cause a restart for the Cisco IP Phones (that are registered to skinny channel). Is the same thing happening with u when u r using sccp channel?

    2) When I called the Phone, it is ringing, when we pickup the handset to answer the call, we hear toooooooooooooooooooo and we do not hear what source is talking and source does not hear us even .. but if we select music on hold, then caller will hear the music. Also, when we tried to use the Ciscp IP Phone to place a call, while we are dialing, the toooooooooooooo tone is always existed and it is ringing at destination but no voice (always toooooooooooooooooooo).

    So, with sccp no problem?

    From the other side, if I need to use sccp (if we assumed the above problems are not existed) then can u please help for below:

    1) If i used sccp and I gave the IP Phone the IP address TFTP server, and no configuration files were existed on TFTP, then it will register on the asterisk sccp channel?

    2) The sccp.conf file, where I can find it? Is it the same as the skinny.conf file?

    3) To use sccp instead of the skinny channel, all what I need is to unload the skinny from the modules.conf file and load the sccp channel in the modules.conf, and I can use the skinny.conf file for the configuration? About the firmware on the Phone, it will stay the same?

    I appreciate the kindly help please.

  • If I need to use SIP, from where to get the suitable firmware for these Cisco IP Phones 7942G?

    Where do u download the SIP firmware usually for your Cisco IP Phones?

    Your kindly help is highly appreciated.

  • You do not need sccp.conf if you are not using chan_sccp.
    It has different features(bugs) than chan_skinny, but yes
    it would also reset the phones (if it supports reload, and
    I have no idea if it does).

    Also if the phone is in a call it will not reset until after
    the user hangs up. Reloading the channel triggers a soft reset
    that causes the phone to request its configuration, which may have


  • Dear Warren;

    It look like u have a good experience in 791x series and in selecting SIP formware, so I am sure you might be able to help in the following:

    As u know, there are SIP firmware for Cisco phones to be used with Call Manager and other firmware to be used with Generic SIP Server (other than Cisco Unified Call Manager). Actually the firmware that start by P0S is that used for Generic SIP Server and that start by cmterm is used for Cisco Unified Call Manager.

    Can I understand from ur blog, that u can use the files that its name start by cmterm to make the Cisco IP Phone to be SIP image that can be used by Asterisk?

    In my case, as the Phones are 7942G, then there are two files are available, really I do not know the difference between them (if u can advise):

    cmterm-7942_7962-sip.9-2-1.cop.sgn (which is written that it is SIP IP Phone load) and cmterm-7942_7962-sip.9-2-1.zip which is written that it is SIP IP Phone firmware files only. So what is the difference between them “the load and the firmware”?

    Now, when I need to do the upgrade for the Phone, then I have to determine in the xml files the needed firmware?

    Appreciate your kindly help.


  • Please, keep all discussions to the list. There’s no need to email me
    personally about this.

    The .sgn file is basically just a zip container that the Cisco Call Manager
    uses. You’ll want to grab the zip file, extract the contents of the file
    into your tftp root directory. The latest firmware that I’ve used was
    8.5.2, in which most everything I needed worked for me. I don’t know
    specifics about the later versions of Cisco’s SIP releases.

    You should have, at least with firmware 8.5.2, the following files in your
    tftproot directory after unzipping the zip file:


    I provide samples of the last two files on the blog post mentioned earlier.
    The last file, that starts with SEP, should contain the actual mac address
    of the phone you are trying to provision. So, for example, it would be
    SEP0003C9DD5624.cnf.xml, if the mac address of your phone was
    0003.C9DD.5624. The example files are pretty much all you need, just go
    through them and change any location specific variables (such as _USER_,
    _IPADDR_, or _PASSWD_) to the proper values for your environment.

    Once you’ve got your tftp server setup properly with all of the appropriate
    config files, plug your phone in and follow the instructions at the bottom
    part of my blog post that explain how to get the phone reflashed to the SIP
    image and registered to your asterisk server.

  • Be careful, not all versions of SIP firmware work with asterisk. I do have 8-3-1
    (cmterm-7941_7961-sip.8-3-1)here and it works just fine with my 7961. Downloaded somewhere. Version 9.x is broken, SIP only works over TCP.

    Search for “cmterm-7941_7961-sip.8-3-1.zip”
    I also have some other files here but I don’t remember what was the reason for them 🙁


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  • I thought that was fixed in the latest 9.x?

    I have a 7961 and just registered at cisco.com then logged in, did a search and was offered the firmware files for free.

    Regards, Patrick