How does my voice come back through my phone when I call someone?

I was on the phone with my best friend when i realized that my voice was coming back through my phone speaker (but not the earpiece/heaphones). This makes sense that I can hear myself because when I talk my voice bounces off the walls around me and my ears pick it up. <br><br>My question is how does my voice come back through the phone speaker? does the microphone in the phone pick up my voice and then somehow send it through the speakers? Is there lag? Does it only send it through the speaker and not the earpiece/heaphones? <br><br>this seems like some sci-fi stuff. My voice is leaving my mouth, being recorded by a microphone in the phone, sent to a satellite in space, then sent back to the phone that is somehow able to differentiate between the voice on the other end and my own voice, and then plays my voice back through the speakers so I can hear it?? <br><br>this is just like star trek where the guys voice comes out of his com device so everyone around him can hear him. I dont know why I never realized this, but now it seems like magic. <br><br>so please explain this like I am 5.