I can’t remember exactly when it happened, but several years ago, Amazon created a system to hide customer email addresses and created an anonymous Amazon-generated email. Using this email is the only way you can contact a buyer (or other Amazon member) via email.
Well, now Amazon is doing the same thing for telephone numbers. Over the next few weeks, you will no longer see an Amazon members actual phone number. Instead you will go through a process called anonymization.
Here is the actual announcement and instructions from Amazon:
You or your delivery carrier may only contact the customer via phone for delivery issues through our phone number anonymization system.
When calling a customer, use the temporary phone number, including the extension if provided, and follow the prompts. The phone number will expire once the package is delivered. This system is scheduled to be rolled out over the next few weeks.
As a reminder, in accordance with our Communication guidelines, you should only contact customers to fulfill an order. If you need to contact a customer for any reason other than package delivery, please use the Buyer-Seller Messaging Service.
Refer to the Prohibited seller activities and actions policy for information about appropriate use of customer phone numbers.
Visit the Help page to learn more.
Note that the phone number will expire once your package has been delivered.
You can still use a package insert to invite a customer to call you as long as your insert does not contain your website (or any way to purchase the product) and informs the buyer to contact you in the event they have a problem.