I am using ffmpeg take audio in from my microphone, rtp stream it to a multicast address as g711ulaw audio, and then play that audio through various devices.

In my network I have other workstations, as well as a digital telephone type device.
My workstations are using Windows.

I am taking the microphone input with this ffmpeg command:
ffmpeg -f dshow -i audio=”” -pcm_mulaw -ab 64k -ac 1 -ar 8000 -f rtp rtp://:?localaddr=

This command transmits the microphone data successfully to other workstations on the network, where I can use ffplay or other means to listen to the rtp stream and hear clear audio.

On the telephone device, when it gets converted to analog to play, it’s picking up this strange, rhythmic burp/clicking/noise, like every time its getting information, its interpreting the header as voice data or something.

The output of the ffmpeg command says the pcm_s16le codec is the native one, and seems to convert it just fine.

Is there any kind of option I should be using in my ffmpeg command that sounds like it could resolve this issue? Or does this kind of interference typically occur for a specific reason?

Its not the hardware, I’ve tested that (other audio able to play clearly).
I’ve tried a few other codecs to no success.
I’ve tried a few ffmpeg options, but there are so many options, they’ve just been successful stabs in the dark