Cisco 7975 - Asterisk 13 compatibility question

Hello everyone. I am trying to get us away from an EOL Cisco UC520, migrating those phones to a FreePBX/Asterisk system using SIP instead of our analog lines. I have started down the rabbit hole, understanding the many apparent pitfalls of trying to get them to work. Boss says we paid for them, it’s what we own, make it work…

So I have started with following a tutorial for Ubuntu server 14.04, compiled everything and it’s Asterisk 13.x. I managed to modify XML files and get TFTP to load up using 8.5.2 firmware. I’m still struggling to even get them to register with the PBX at all. I then came across the wiki page here:
sounds like I need to be on a custom patched Asterisk 11, using chan_sip for them to have any chance at all to work.

I am requesting help from anyone kind enough to at least verify the requirements of what I need to have/do for this particular setup to be functional. There’s a vast amount of information out there, a lot of it old and some of it conflicting. I appreciate any help that anyone can give me in moving forward.


If you are using 7975 phones, you might consider Chan-SCCP-B as your interface. This is a Skinny Interface that you can add to Asterisk.

I’m once again in the process of writing a FreePBX Manager for Chan-SCCP-B, so in a few weeks there will even be a management module for it again (the one I wrote for Version 1.8 has some “issues”.)

Check the WIki Pages on the Chan-SCCP-B SourceForge page. If that’s something you might be interested in, there is a page there that discusses adding the module to a FreePBX based system. Message me if you have questions.

I did indeed come across the CHAN-SCCP-B in my scouring of the internet. I just am too new to really have figured out how to make use of it or if it would be of any help. Since this post, I did manage to get them registered with chan_sip, and able to call internally. Does CHAN-SCCP-B give more functionality then? I would gladly help test, I will go check out the sourceforge page and see about adding in that module as an option.

The channel driver is in constant development and doesn’t really need a lot of testers. The SCCP Manager, on the other hand, is still at the “how do I get Helloworld to make these changes” stage. It’s going to be a while before I’m ready to test.

As far as “why would you choose Skinny over SIP?” The phones just work better. You can change the buttons, the BLFs work without having to patch the native Asterisk Code, and the driver works with the “asterisk-devel” package that is available for FreePBX’s particular version of Asterisk.

There are a couple of places where SIP is better for these phones, but even these are not really advantages. For example, you can set the phones up to use passwords to log in with SIP (even though the 8 character password limit is a real threat) so you can have your phones outside your local network. Actually, I guess that’s it.

Overall, I’ve used both the SIP and SCCP versions of the phones and I find the SCCP versions just work more reliably. Now, from a deployment perspective, there are some Cisco devices that don’t have a SIP load (the 7910, for example), so when I was putting in a deployment of for a company that had phones already (and a couple 7910s in the break rooms), I found the old-old-old version of Chan-SCCP-B to just work.

I’m a minority in this - for the most part, people are happy with the limits of the SIP load and just motor along happily with the phones doing what they do. I prefer the SCCP driver for them and the Skinny loads for the phones. I just seems to make for a more versatile and simpler network (even without a GUI manager).