The upgrade path has changed a little bit since the new options of "pluggable" asterisk versions, meaning we now can swap between version without affecting the other components of Issabel (in the past if you attempted to remove asterisk due to a dependency chain you would end with a shiny centos minimal install after all the package removals).
I strongly discourage using rpm --nodeps as there are some dependencies needed on the newer versions.
Plus you should be able to install asterisk11 or asterisk13 (that is how they are called now) via yum with the beta repo enabled
We are working on new documentation to be released, but it takes some time to get it done, hopefully we'll have news about that soon.
Thank you so much for the tips you are constantly sharing on the forums, they are greatly appreciated.