前陣子的報料，美國的電信商提供 API 給第三方，讓第三方可以用 IP address 查出你的真實身份：「Want to see something crazy? Open this link on your phone with WiFi turned off.」，像是這樣：
These services are using your mobile phone’s IP address to look up your phone number, your billing information and possibly your phone’s current location as provided by cell phone towers (no GPS or phone location services required).
目前所有的網站都已經被下架了，但可以從當時的截圖看到有多少資訊。AT&T 的新聞稿在「AT&T Helps Businesses Improve Mobile Transaction Security with New Mobile Identity API Toolkit」，新聞稿沒被下掉我猜可能是因為上市公司受法令限制的關係？
But what these services show us is even more alarming: US telcos appear to be selling direct, non-anonymized, real-time access to consumer telephone data to third party services — not just federal law enforcement officials — who are then selling access to that data.
而且作者在 GitHub 上看到有程式碼針對韓國電信商提供的 API 呼叫，所以韓國也有類似服務：
I found what looks like a third-party API implementation for a Korean Danal API on GitHub. The author wrote the code for South Korean telcos, so there may be differences with US carriers. The query parameters in the HTTP requests are similar to what I remember seeing in the Danal demo. It’s unclear from my reading of the code whether or not this API requires operation inside of e.g. a Danal Inc. hosted-iframe for identity confirmation. The diagram on page 4 of this documentation describing the Korean “Danal Pay” service appears to show the client interacting with the customer’s servers only.