https://blog.wongcw.com/2021/11/25/verizon%e8%88%87att%e6%8f%90%e8%ad%b0%e6%9a%ab%e6%99%82%e9%99%8d%e4%bd%8e5g%e5%9f%ba%e7%ab%99%e5%8a%9f%e7%8e%87%e4%bb%a5%e9%81%bf%e5%85%8d%e5%b9%b2%e6%93%be%e5%88%b0%e9%a3%9b%e6%a9%9f/