HAAst is a commercial tool, targeted at large and commercial call centers. These environments don’t use Rasberry PI’s, so we haven’t compiled for the PI yet.
FreePBX targets home and small office installations (large commercial call centers don’t generally use FreePBX). However, as some of our developers are PI enthusiasts at home, we may chose to offer a free version of HAAst for the PI some day. But this would be a hobby version only!
If you are using a PI and want HAAst, please post to tell us the Linux distro & version you are using on the Pi (so we can figure out what to compile for).