I needed Yeti to emit a Q.850 Reason header alongside a SIP disconnect code (when call fails inside Yeti, not a downstream class 5 switch), so I implemented it on v1.13. Now that I want to upgrade to v1.14 it’s a bit of a pain. So I would like to contribute this patch to sems-yeti and yeti-web the project (mainly so that I can later upgrade without this pain to new version, and maybe this would also be useful to someone). What’s the process to contribute? Just opening PRs in Github? If so do I do that against master or some other branch/release? I see latest is v1.14 but v1.15 is in the works.
Also I’m working on an EVS codec module for IMS ICs. Progress is slow but I would like to contribute that too someday. 
yes, open PR on github, to master branch.