Security: How to prevent sim swap hacks?

How does one go about to prevent a sim swap hack? Seeing stories online how easy it can be. All it takes is a call to customer service and find the right person who are normally underpaid and overseas and will do it for customer service.

How can I lock my phone number? My primary number is Google voice so I feel a bit more secure because txt messages are delivered to my gVoice # which itself has 2FA but phone calls are routed to my primary cell phone number.

For example my wife doesn't have gVoice as her primary. Can the carrier lock this? Is there a service which will lock your #?

2FA is so insecure with mobile. I called my carrier and could not understand the guy speaking and he didn't seem knowledge able

I put a lock pin on my phone but that doesn't prevent it from transferring over.

How do you secure your accounts? It almost like you need a 3FA .. 2FA for your 2FA.

Thoughts recommendations? Even searching here I didn't find clarity.