On Monday, May 9th, 2022, an intermittent issue involving voip.freephoneline.ca began affecting incoming calls, which would drop immediately to FPL's voicemail system.
I did report the problem to someone at Fongo.
If you experience the same problem, I suggest switching to either "voip4.freephoneline.ca:6060" or "voip2.freephoneline.ca" without the quotation marks.