My system is a Linux (PCLinuxOS) laptop (KDE4-64).
I noticed, at least with 14.0.5.0 and 14.0.6.0, when using the Google Hangouts app to make calls, it doesn't produce rings tones anymore when the call is made.
However, when a call is made to my Hangouts number it does produce the ring tone.
Hangouts had been working with slimjet before, though I haven't tested to determine which was the last version it worked on.
I also tested using Hangouts with the latest Chrome browser, and it worked with no problems.