I work from home and make a lot of phone calls. Every once and a while I'll get garbled voice for around 5 to 10 seconds and it'll go away. It happens multiple times a day and usually once or twice per call during my avg hour long conf calls. I'm using an analog phone, so no other way there could be interference. It's rather annoying.
I've had this issue for the past year, but haven't done anything about calling VZ about it. I don't have any issues with voice or video and my ONT has been replaced a few times for other reasons.