Comment 12 for bug 429510

To fix the missing dahdi module issue, correctly, you will need to install the linux headers for the kernel version installed:

1. uname -r ##to find out the kernel version (e.g., 2.6.31-20-server)
2. sudo apt-get install linux-headers-2.6.31-20-server
3. If you already have the dahdi and asterisk installed, then apt-get should also automatically finish the previous install.

The last comment with the order of installation only gets rid of the error message when installing other programs that have dependencies on the dahdi module. Hope this explanation helps you out!