How do I fix an echo on a Galaxy S5 mini?

[AC Question]

I recently had to replace my phone. I got a new one and callers are telling me they heard an echo of their voice. Basically, it was fine on my end, but people I called would hear themselves twice. I took it into U.S. Cellular and they couldn't fix it, so I got another phone replacement. My new phone is doing the exact same thing.

1) I have disabled Talk Back and made sure it is in "disabled" apps.
2) I have unchecked the noise reduction setting.
3) I tried to access speakers via things I saw on the internet, but couldn't find a the "accessories" setting, and I don't know if that would even make a difference.

Any ideas?

 

[Rukbat]

Keep having it replaced until you get one that works.

Have a friend who can spend an hour getting calls from you, ready to work with you when you go. Get the new phone, call him and if there's still an echo, the store employee can hear it, junk another phone and open another box. When they run out of S5 minis a dozen times, they'll send the complaint up the line, and Samsung will listen to US Cellular's CEO complaining that Samsung is costing them a fortune.

You can't get Samsung to do anything, the store can't, but the company can - because they can sue Samsung for their cost of replacing your phone 500 times. (I used to own cellphone stores and when we got a model that had a defect like that (the Motorola W385 was one, as I recall, so was the original Razr V3 [they fixed the absolutely awful battery drain issue eventually]), I'd eat the cost of upgrading the customer to something that worked, charge my supplier for the difference and refuse to carry the phone, letting the carrier district manager know why. Phones get fixed that way.)