I had this pleasure to Upgrade from Lync 2013 to Skype for Business #Skype4B for a few weeks ago.
When it comes to Competella server, the frist I did was that since we was on R1, I had to build a New Competella server based on the Lync 2013 install. When tested that one and it Works, we then start to plan for the Upgrade.
After all Lync 2013 servers was upgraded then we started on Competella server. We then upgraded the UCMA and moved the pool, running at the same procedure as we did on the Lync 2013 installation.
Then we had to reboot the server and get in the patches.
Then it seems like working, but then we discovered that some services in Competella did not work.
Some dialog With Competella Support, well and then we had to install the Competella up on the New UCMA even we had it on Place when we had it installed.
But anyway, this make the Magic working.....Thanks to Thomas Stubergh my co-worker at Skill AS and to Competella support who sloved this for us.