This similar issue was posted in another thread, but I wanted to get it on this thread, so, apologies if you find it a duplicate.
Telephone comes off mute every 12 to 15 minutes during calls.
When recording a meeting or presentation using local software such as
Screenflow, Telephone is used to dial into a conference line and capture
the dialogue. (with full disclosures to the group btw). Then another, separate land line phone is used to dial
into the same meeting for talking with the group. To avoid feedback, the
computer audio is set to mute, and the M command on the Telephone app
is used to mute the app. This still captures the audio on the conference
line, because the app and landline, as well as the other parties are
all dialed in to a conference line, and while Telephone is muted, it
serves as the input capture for sound from the conference call.
It's
pretty cool. But for the last year or two, maybe early 2014, the
Telephone app comes off mute unexpectedly, and as quite a few others
have noted, while still showing mute status. The effect is a range of
feedback, to full garbled distortion of the call. The only change for me
has been mac os x upgrades from say, Mountain Lion through Yosemite.
This issue is replicated on at least three other Mac laptops, from a
Macbook air 2014, to Macbook Pro 2010 and Macbook Pro 2014 among others.
In another thread, Shaf suggested the issue occurs when making another call,
however in our case the other call is from a separate, handset phone dialing
into a shared conference line so it should not affect the Telephone app
performance. The call comes 'off mute' about every 12 to 15 minutes and
is very, very disruptive to our meetings.
On Monday, May 19, 2014 at 5:27:10 PM UTC-4, Von L. wrote:
I had the same thing happen to me today. Multiple people using Telephone.app 1.1.4 (114) on Mac OS X 10.9.3 and several people complained that we could be heard even though the app said "mic muted"
Anything I can provide to help troubleshoot, please let me know.