Share your experience!
Hi @Cool2hate, very sorry to hear about your phone. 
When the phone has been sent for repairs, has the service centre changed any parts in the phone or have they not been able to find the cause of the echo during calls?
Does this occur in every call you make or can you place 10 calls and there is no echo at all in those calls and then the next call has echo? If that is the case, try temporarily and change the network mode in your phone. You can do that in Settings > More > Mobile networks > Preferred network type > WCDMA Only. If you have another SIM card that you can try in the phone that would also be a good way to see if this is caused by the network or not.
Let me know how it went!
Service said they changed mainboard of phone. And screen changed for another reason. But both of these changes didn't work.
It generally disappears in first 10 sec.s sometimes not. Nearly all calls starts with echo and diasappears in 60% of calls. I used same sim card with another phone without any problem while telephone was at repair. I checked settings but it don't show WCDMA only but shows 4.5G(prefered)/3G/GSM or 4.5G/3G and all like this.
Sorry that I didn't post last update. My phone also change main board and screen. But now it work properly. Also two time at service center. But I see on screen has one white dot since the last screen and with the new one it still appear.
Hi again @Cool2hate, thanks for the great information!
If you have another SIM card that you can try in the phone that would be the best, even if it works fine in a different phone.
Oh, that is my bad, 3G is sometimes called WCDMA, I forgot to mention that in my previous post.
There should be an option called "3G only" that you can change to and make a few calls and see if there is still an echo in the start of the call.
@Kreng, I'm glad to hear that it is working now again, sorry to hear about the dot though. 
Is the white dot always visible or can it only be seen in certain applications? You can try and run the screen test in the phone which you can find in Settings > About phone > Diagnostics > Test > Display.
Is the white dot visible here as well?
Keep me posted!
I couldn't try with anothe sim card because I couldn't find any other sim card as small as XZ have. And 3G only still echoes.
I plan to visit service for 6th time next week....
Thanks for the update @Cool2hate!
I'm very sorry to hear that you have had to visit a service centre that many times, I'm afraid that my recommendation is that you visit it again.
I'm afraid that I'm not well informed on consumer laws in market/region since I'm based in the Nordics, have you been in touch with your Local support team regarding that you have had to visit a service centre that many times?
If you haven't done that, I'd recommend doing so. They are very well informed on consumer laws, local service routines and so forth in your market/region and will be able to give you are more exact answer on how to proceed with this.
Feel free to keep me posted on how it went!
The person calling me can hear his own voice
Hi @SHANE1, sorry to hear about this. 
Have you tried any of the troubleshooting that I have previously posted in this thread? If you haven't, I would recommend doing that you start with the microphone test.
/t5/Xperia-XZ/Echo-during-call/m-p/1199397#M5188
Let me know how it goes!