To back up your old Viber calls, you can try the following steps:
- Open Viber on your Windows device.
- Go to the "More" tab.
- Choose "Settings".
- Select "Calls and Messages".
- Tap on "Email message history".
- Enter your email address and click "Send".
- You will receive an email with a backup of your Viber calls and messages.
Note: If your old Viber calls are not shown in your Viber account, it may not be possible to back them up.