隨著網路服務的普及以及智慧型手機的價格降低，幾乎人人都可以負擔智慧型手機，而使用者對於即時通訊的需求也漸漸浮現，市面上也有越來越多的通訊軟體提供IM (Instant Messaging) 或VoIP (Voice over Internet Protocol) 的服務。
各式各樣的App 被設計出來滿足不同的使用者需求，但是不管是IM或者是VoIP以及其他通訊軟體不可避免地都會導致網路的使用量增加進而讓使用者的電信資費成本上升。
為了節省使用者的成本，我們提出了一個嶄新的通訊系統稱為雲端橋接系統，此系統囊括了網路服務以及原有電話網路的好處，系統利用網路發送通話請求給 Web server 接著利用SIP (Simple Initiation Protocol) server把通話重新導向到 PSTN (Public Switched Telephone Network)，藉此來降低網路封包的流量。
在這篇論文的一開始，會先介紹雲端橋接系統的架構，之後會著重於iOS客戶端的MVC (Model-View-Controller) Structure 、SIP client和多人即時會議管理的實作。並且詳述各種通訊的情況，以及如何讓使用者有效且方便的掌控會議的餐與人員和狀況
最後，我們實作出了這個系統，並且改善了它處理使用者資料的效能使得此App對使用者為Fully UI-Responsive 以及有效地提供使用者即時會議的狀態和會議的管理。

With the pervasive use of the Internet services and the fact that the mobile devices are affordable for almost everyone, social communications like IM (Instant Messaging) and VoIP (Voice over Internet Protocol) through the Internet therefore become more and more thriving.
A variety of applications have been developed to cater to all kinds of user needs, but the increasing usage of network is inevitable and so is the cost of monthly fee.
In order to save the user’s cost, we have developed a system called CBS (Cloud Bridging System) that takes advantage of both the Internet service and PSTN (Public Switched Telephone Network) service by sending the requests of call by apps and redirect the phone calls to PSTN by SIP (Simple Initiation Protocol) server and hence lowers the usage of Internet.
This thesis starts with an introduction to the whole system and then focuses on the implementation of the client side software on iOS smart devices including the MVC (Model-View-Controller) structure, SIP client and the conference arrangement.
This thesis proposes a novel cloud-based online communication system, which can lower the usage of the Internet service while enhances the quality of communication. By using the proposed system, users can easily start calls or initiate conference calls and host the conference calls by apps.
At last, we improve the app’s performance to handle the contacts’ data to make it fully UI responsive to user and provide real-time status of every user in the conference call for host in an efficient way.

Chapter 1 Introduction ................................................................................................. 1
Chapter 2 Related Works.............................................................................................. 4
2.1 PJSIP ............................................................................................................................ 4
2.2 Web Service................................................................................................................. 4
2.2.1 Overview .............................................................................................................. 4
2.2.2 UDDI ..................................................................................................................... 5
2.2.3 WSDL .................................................................................................................... 5
2.2.4 SOAP ..................................................................................................................... 6
2.3 Tomcat Web Server ..................................................................................................... 6
2.4 MongoDB .................................................................................................................... 7
2.5 Conference Call ........................................................................................................... 8
Chapter 3 System Architecture ................................................................................... 10
3.1 CBS (Cloud Bridging Switch) ....................................................................................... 10
3.2 SIP Server .................................................................................................................. 14
3.3 Web Portal ................................................................................................................ 15
3.4 Client-Side Software .................................................................................................. 15
3.5 System Architecture Overview ................................................................................... 16
3.5.1 Notification Service Server .................................................................................. 16
3.5.2 SIP Server Bridging .............................................................................................. 17
3.6 Calling scenarios ........................................................................................................ 18
Chapter 4 System Implementation .............................................................................. 21
4.1 Core Data Overview ................................................................................................... 21
4.1.1 Introduction ........................................................................................................ 21
4.1.2 Core Data stacks ................................................................................................. 21
4.1.3 NSPredicate ........................................................................................................ 24
4.1.4 NSSortDescriptor ................................................................................................ 24
4.1.5 NSFetchRequest .................................................................................................. 25
4.1.6 NSFetchedResultsController ................................................................................ 25
4.2 Concurrency issue ...................................................................................................... 26
4.3 Multi-thread implementation .................................................................................... 29
4.4 App Design ................................................................................................................ 33
4.4.1 MVC Design Rule ................................................................................................. 33
4.4.2 General Design.................................................................................................... 33
4.4.3 KITs and KITs Abroad ........................................................................................... 36
4.4.5 Concall ................................................................................................................ 36
Chapter 5 Graphical User Interface ............................................................................. 38
5.1 KITs and KITs Abroad ................................................................................................. 38
5.2 Concall ....................................................................................................................... 43
Chapter 6 Conclusion and Future Works .................................................................... 47
References ..........................................................................................................................

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