The patch was becoming difficult to manage once there was more than one engineer working on it so we forked kamailio and applied our patch. The intent is still to push it upstream once we clean out some of the changes we currently need in other modules (as well as maybe make it more generic).
It is available in completion at https://github.com/2600hz/kazoo-kamailio. To keep people from finding it and not knowing it’s a modified kamailio we keep all the code on branches.