Cisco 7941 phones and PJSIP - Solution

You could also use Chan-SCCP-B instead and leave the phone in Skinny mode.

The config files that come with the driver are pretty good.
The FreePBX Manager for it also works very well.

With the recent addition of the IP Address settings for Option 66 and 150 in Sysadmin Pro, it’s a rock-solid configuration.