Cisco Phone 7940G TFTP Size Error


I have a Cisco 7940G and I am trying to upgrade it to SIP. I am getting an error that says: TFTP Size Error. I am gonna use my FreePBX Server for the SIP configurations (If I ever get it upgraded). The year of the Phone is 2000 (I think). I do NOT have a Cisco Contract. So how would I upgrade to SIP successfully without any errors?

Keep in mind that I’m the sole voice my particular wilderness, but these phones were never designed to run SIP, and the SIP image that Cisco provides has some problems. It was deliberately designed to make the transition from SCCP to SIP harder.

If you go to GitHub and look for Chan-SCCP-B, you should find the program information and a Wiki page there that talks about how to run these phones in their native “Skinny” mode using a new channel driver under FreePBX. There is no graphical interface that works with Version 13, but the config file (or files, if you set it up that way) is logical and relatively easy to use. If you decide to go that way, you can PM me with questions.

@cynjut Your not the only voice in this wilderness. Your assessment of it is correct though.

I’ve gotten phones to successfully use SIP and they are broken as hell once connected. You will be dealing with constant issues and support tickets. Soon you will wish to smash them all with a sledgehammer to make your life easier. I’d say to use what Cynjut recommended or buy a different phone if you want to use SIP. After a month of fiddling around with SCCP we got the cisco phones to work decently on SCCP.

@adtopkek - thanks.

If I remember, a lot of the problems you had weren’t necessarily problems with the channel driver or the configuration of the files, it was understanding how the pieces fit together. It doesn’t take most people more than a few hours to install the software and set up their first phone. If the Wiki I wrote isn’t right, I’ll fix it, but I use it every time I install a new Chan-SCCP-B instance, so it’s usually pretty close.

The developers of Chan-SCCP-B are very responsive, and I’m available to do PM tech support. They are constantly working on the driver and have lots of success stories with various Asterisk-based implementations.