Dear community,
I was looking through the internet, but i could not find a proper answer for my question. That's why you are my last hope 
Is there any examples that i can use my Arduino to Real time talk into a microphone and on speakers i can hear same message? I found a lot of talking in projects to blink a led, but i would like to have like a "telephone"
Thank you guys!
...to Real time talk into a microphone and on speakers i can hear same message?
That's a PA system or a bullhorn and there's no need for a microcontroller.
...And, the Arduino isn't fast-enough for real-time audio.
...but i would like to have like a "telephone".
Again, land-line phones are mostly analog (you could use the Arduino to make the touch-tones for dialing). Cell phones are very complex although you can get a GSM shield to do all of the "work".
You can sample ADC and output on a DAC using an arduino DUE at 44.1 KHz. You might also consider this tutorial for a bipolar ADC/DAC :
or you can interface a CODEC in I2S (SSC peripheral) with an external ADC/DAC.
Is there any examples that i can use my Arduino to Real time talk into a microphone and on speakers i can hear same message?
Sure but you can do much more than that.
From chapter 15 of my book Arduino Music and Audio Projects | SpringerLink
