To add my experience to the subject of this thread: I use my OPN 1s for telephone calls much more frequently than I initially anticipated. I can hear WAY more clearly than I could with my landline + binaural headphones + amplifier. HAs are paired with iPhone 7 without software update that I keep getting reminders for (sorry forgot number). Many of my calls are multi-party conference calls, and some last over one hour. As stated in other threads, this situation is often challenging for us.
I get drop out infrequently. I estimate average once every half hour to 45 minutes. Always just one ear, can be R or L. Typically lasts about 15 seconds. then seems to self correct and sound is restored to both ears. I’ve tried to be alert to what is causing this, and I can’t detect any cause. I don’t detect any loud or abrupt sound on the call or in my surroundings. I’m usually near a computer, but nothing unusual there seems to correlate with the drop out. I don’t consider this enough of a problem to seek a fix because I can always hear more-or-less OK with one ear for the brief period of the drop out. And I seldom use my HS’s for music, Etc.