Voice over IP for Sony Ericsson Cellular Phones

This report presents an investigation of the possibilities to implement voice over IP (VoIP) in Sony Ericsson cellular phones. The results from this investigation show that it is partially possible to implement such a solution. The best option for doing so is to make use of the support for the Session Initiation Protocol and the Real-time Transport Protocol offered by the architecture. Another goal is to evaluate if Bluetooth is able to handle the requirements needed for the solution. The whole concept is proven by implementing a prototype. Measurements on this prototype show that Bluetooth will be able to
handle the requirements of most IP-based voice communication,i.e., in respect to latency and bandwidth.

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Author: Petter Theander, Thomas Hultgren

Source: Blekinge Institute of Technology


1 Introduction
2 A Need For New Communication Technologies
2.1 Circuit-switched Networks
2.2 Packet-switched Networks
2.3 The Internet
3 The Initial Idea
3.1 Background
3.2 Vision
3.3 The Basic Idea
3.3.1 Making an Outgoing Call
3.3.2 Handling Incoming Calls
3.4 Technical Requirements
3.4.1 The Cellular Phone
3.4.2 The Base Unit
4 Investigating the Options
4.1 Interview Methodology
4.2 Interview Results
4.3 Investigating the Current Architecture
4.4 IP Multimedia Subsystem
4.4.1 The SEMC IMS Architecture
5 Design of the VoIP Prototype
5.1 Solution Design
5.1.1 Maintaining Flexibility and Modularity using SIP
5.1.2 Using SIP and SDP for Negotiating the Media Format
5.1.3 Bluetooth with IP Capabilities
5.1.4 Overview of the SIP Solution
5.2 Prototype Design and IMS Relationship
5.2.1 SEMC IMS Client Interaction
5.2.2 IMS SL and the VoIP Server
5.2.3 The VoIPCore Component
5.2.4 The VoIPMediaHandler Component
5.2.5 The VoIP Callback Interface
5.3 Scenarios
5.3.1 Registering with a SIP Registrar
5.3.2 Sending a SIP Invite Request
5.3.3 Starting the Media Session
5.3.4 Requesting to Talk
5.3.5 Incoming Request Talk
5.3.6 Incoming SIP Invite Request
5.3.7 Sending a SIP Bye Request
5.3.8 Incoming Bye Request
ii6 Prototype Implementation
6.1 Bluetooth Connectivity
6.2 The VoIP Prototype
6.2.1 Changes in the Underlying Architecture
6.2.2 No Support for Full-duplex Audio
7 Evaluation of the Prototype
7.1 Answers to the Research Questions
7.1.1 Reasonable Response Times
7.1.2 Possible to Implement IP-Telephony
7.1.3 Support for New Communication Technologies
7.2 Suggestions for Further Research
8 Discussion and Related Work
8.1 Network Address Translation
8.1.1 VoIP in NAT Situations
8.1.2 Avoiding the NAT Problem
8.2 VoIP Security
8.3 Public Safety
8.4 Related Solutions
9 Conclusions
A The Session Initiation Protocol
A.1 Introduction to SIP
A.2 The Architecture of a SIP Network
A.2.1 User Agents
A.2.2 Registrars
A.2.3 Location Servers
A.2.4 Redirect Servers
A.2.5 Proxy Servers
A.3 Signaling in SIP
A.3.1 Responses
A.3.2 Requests
A.4 SIP Message Format
A.4.1 Request Line
A.4.2 Status Line
A.4.3 Headers
A.4.4 Bodies
A.5 Bridging SIP and the PSTN
B The Session Description Protocol
C The Real-time Transport Protocol
D Glossary

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