$540 via promo credit when you add a new smartphone line with your own 4G/5G smartphone on postpaid Unlimited Plus plan between 5/18/23 - 5/31/23 & port-in req'd. Promo credit applied over 36 months; promo credits end if eligibility requirements are no longer met.
Symptom was that the person on the other end of my calls heard their voice echo. I found that the problem only occurred with one of my headsets. No problem with a different headset and no problem when I had no headset connected.
After spending two days in various forums I found that I could stop the echo problem by turning off Advanced Calling.
SETTINGS=>ADVANCED CALLING=>ADVANCED CALLING=>HD VOICE (remove the green check).
glad you figured it out