At McMurdo, phones have access to a wifi network only for wifi calling and texting, not for general Internet access. It’s just a prototype at this time. It doesn’t work in all cases or in all areas, and for one reason or another it doesn’t work for some people, even if they’ve followed all the steps for enabling wifi calling.
看起來作者遇到的問題是 latency 過高以及頻寬不穩定的問題：
Also, the protocol assumes terrestrial broadband with reasonable latency and bandwidth. At McMurdo, as of this writing, latency to terrestrial locations is in excess of 700 milliseconds. Usable bandwidth for any given end user can vary widely, down to a few dozen kilobits per second.
然後也很難 troubleshooting：
The protocol also doesn’t expose any useful diagnostic info to the end user in order to troubleshoot. You just have to cross your fingers that the magic “wifi calling” icon lights up.
接下來作者嘗試的是 Voice MFA，但不存在這樣的電話號碼可以轉接之類的：
Direct inward dialing to US Antarctic stations isn’t generally available, so you probably can’t configure your cell phone number to forward to a number you can directly answer on-station. (I’m aware of some exceptions to this.)
A short code typically contains between three and seven digits, depending on the country or region that it's based in.
要注意的是短碼的部份需要開 support case 申請，而不是直接在 web console 上操作：
Open a case with AWS Support by completing the following steps.
長碼則是有可能到 12 碼，依照不同地區的設計有所不同：
A long code (also referred to as a long virtual number, or LVN) is a standard phone number that contains up to 12 digits, depending on the country that it's based in.
不過現在長碼的部份只有美國可以用，而且有速率限制：
Support for long codes is restricted to the United States only. Sending rates for long codes are restricted to 1 message per second. This restriction is set by the telecom carriers, and isn't a limitation of Amazon SNS. If you send a large volume of messages from a long code, wireless carriers might begin to block your messages. Your applications that use Amazon SNS should limit the number of messages that they send each second.
O2-Telefonica in Germany has confirmed to Süddeutsche Zeitung that some of its customers have had their bank accounts drained using a two-stage attack that exploits SS7.
