Can I have my primary number if not available automatically call the secondary

Call Forwarding for Voice Calls is a Carrier Specific feature please contact your Carrier to understand this feature better.

Here are the steps on how to set up voice call forwarding to another number:

1. Check with your carrier. Not all carriers offer call forwarding, so you'll need to check with yours to see if it's an option.
2. Find the call forwarding settings. The exact steps for this will vary depending on your carrier and phone model, but you'll usually find the call forwarding settings in your phone's settings menu.
3. Choose a call forwarding type. There are different types of call forwarding, such as always forward, busy forward, and no answer forward. Choose the type that best suits your needs.
4. Enter the number you want to forward your calls to. This can be any phone number, including a landline, mobile phone, or Google Voice number.
5. Turn on call forwarding. Once you've entered the number you want to forward your calls to, turn on call forwarding.