Voices between clients don't reach each other in my TS3 server

Hello, I am new to hosting my TS3 server for ARMA.

In my server, a speaker looks he can talk without any problem but others cannot hear speaker.
I suspect some channel setting should be required but found no documentation regarding this issue.

Check if the Playback Device is set in the options on the client where your sound is turned off.
ToolsOptionsPlaybackPlayback Device

Sorry for confusion but this situation occurs even not a deaf client is an audience.
My Android client can speak but cannot hear my PC client and vice versa while their client device config looks valid.
They can light their own speaker lamp but audience cannot see it.

You have problems with the output sound on your phone, check the sound options on your phone.
And one more question, do you use speaker or headphones?

If you still have problems, please leave more information about your phone. ( e.g. Brand, Model, Version )

The crossed microphone Icon next to the channel means that the channel is silenced.
When an amount of users in it, the voice channel is silenced.

Someone set this up that way in the server settings