Local overlays should be managed via /etc/portage/repos.conf/.
To enable this overlay make sure you are using a recent Portage version (at least 2.2.14), and create an /etc/portage/repos.conf/ring-overlay.conf file containing precisely:
[ring-overlay]
location = /usr/local/portage/ring-overlay
sync-type = git
sync-uri = https://github.com/stefan-langenmaier/ring-overlay.git
priority=9999
Afterwards, simply run emerge --sync, and Portage should seamlessly make all our ebuilds available.
Invoke the following:
layman -f -a ring-overlay
Or read the instructions on the Gentoo Wiki.
After performing those steps, the following should work:
sudo emerge -av net-voip/gnome-ring
There are two kind of ebuilds available. The live ebuilds (with version 9999) are taken directly from the git master branch (and in case of the ring-daemon are compiled with the bundled libraries). The stable ebuilds are from fixed versions and have been tested to work together. As a bonus they try to unbundle the application as much as possible.