近年來語音通訊的技術越來越成熟，隨著訊息傳播越來越頻繁，資訊安全已成為非常重要的議題。在現代化的社會中，手機已經成為了人人都有的通訊裝置，不管是在通訊、購物、休閒娛樂，都離不開手機的使用，所以手機通訊時的安全與否將是人們值得關注的議題。本研究將會以Voice over Wi-Fi通訊技術為背景(以下簡稱VoWiFi)，研究VoWiFi在通訊中的協定以及驗證潛在的風險，並設定四種不同的環境，針對是否連接電信網路、使用VoWiFi通訊技術的一方為發話方或受話方，丟棄通訊時的語音方包和重要的SIP訊息封包，詳細的說明各個封包遺失時對發話方、受話方所造成的影響，並提出演算法供未來開發APP或設備來偵測通話環境是否安全、建議電信商加入偵測機制來保障使用者權益。

In recent years, the technology of voice service has become more and more mature. With the increasing frequency of information dissemination, information security becomes a very important issue. In modern society, mobile phones have become communication devices for everyone. No matter for communication, shopping, or entertainment, mobile phones are inseparable. Therefore, the safety of mobile communication is a topic worthy of attention. This study discusses the security issue about Voice over Wi-Fi communication technology (hereinafter referred to as VoWiFi) to examine the protocol of VoWiFi in communication identifying the potential risks. This study sets four different scenarios for whether the Caller or the Callee connects to the telecommunications network or VoWiFi. We discard voice content packets or critical SIP message packets when the user uses VoWiFi communication. Then, we observe the outcome and find the variations of message sequence in detail affecting on the Caller and Callee at each lost packet. We design an algorithm for the future development of APP or device to detect whether the calling environment is secure or under attack. With our experience, we recommended that the telecommunication service provider should employ the similar detection mechanism for security.

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