Microsoft is changing [microsoft.com]
Cortana service on Surface Headphones (First version) for customers in the United States and some skills will no longer be available starting in early 2021. Impacted customers in the United States may claim a promotional $25 [bing.com]
Microsoft Store Online gift card.* Use this site to check that you meet the eligibility criteria and submit your claim by July 30, 2021.
Find the serial number with Cortana:
Find the serial number on Surface devices. [microsoft.com]
- On a Windows 10 PC: Open Cortana, select Devices > Manage Surface Headphones. Under About, look for the serial number.
- On an iOS device or Android device: Open the Cortana app and select Devices > Devices > Surface Headphones > Surface Headphones > About.
See full Gift Card Program Terms [bing.com]
- You must provide a valid serial number for a set of Surface Headphones (First version) purchased from an authorized Surface retailer in the US; and
- You must be the owner of the latest US-based Microsoft account used to set up Surface Headphones (First version) and send a voice request from your Surface Headphones to the Cortana service after July 31, 2019; and
- You must submit a completed claim form to Microsoft as instructed between July 31, 2020, and July 30, 2021.
on the Gift Card Program for Surface Headphones (First version) Owners redemption website.