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目录
摘 要 ····························································································· iii Abstract···························································································· iv 第1章绪论 ······················································································· 1 1.1 课题的研究背景 ································································································· 1 1.2 课题研究意义 ····································································································· 1 1.3 课题研究的目标 ································································································· 2 1.4 主要研究工作 ····································································································· 3 第2章 融合通信理论基础 ··································································· 4 2.1 VoIP技术概论 ···································································································· 4
2.1.1 VoIP技术产生的背景 ·················································································· 4 2.1.2 VoIP技术的原理 ·························································································· 4 2.1.3 VoIP技术的特点 ·························································································· 6 2.1.4 VoIP技术的发展趋势 ·················································································· 6 2.2 软交换技术概述 ································································································· 7 2.2.1 软交换技术产生的背景 ·············································································· 7 2.2.2 软交换技术的概念 ······················································································ 7 2.2.3 软交换技术的功能 ······················································································ 7 2.2.4 软交换技术的意义 ······················································································ 8 2.2.5 软交换技术的应用 ······················································································ 8 2.3 会话初始协议（SIP） ····················································································· 10 2.3.1 SIP协议的背景 ·························································································· 10 2.3.2 SIP协议的功能 ·························································································· 10 2.3.3 SIP协议的网络元素 ·················································································· 11 2.3.4 SIP协议的实现机制 ·················································································· 12 2.3.5 SIP协议的消息组成 ·················································································· 14 第3章 企业IP融合通信方案设计 ························································ 16 3.1 需求分析 ··········································································································· 16
3.1.1 背景 ············································································································ 16 3.1.2 企业需求 ···································································································· 16 3.1.3 实现目标 ···································································································· 16
***计算机科学系毕业论文
3.2 方案设计 ··········································································································· 17 3.2.1 网络拓扑结构 ···························································································· 17 3.2.2 安装说明 ···································································································· 17 3.2.3 设备选型 ···································································································· 17 3.2.4 拨号规则设置 ···························································································· 19 3.2.5 企业IP融合通信需要考虑的技术问题 ··················································· 19 第4章 方案具体配置及设置 ······························································· 23 4.1 配置流程 ··········································································································· 23 4.2 具体配置 ··········································································································· 23 4.2.1 实验室环境说明 ························································································ 23 4.2.2 企业总部设备配置 ···················································································· 24 4.2.3 企业各分部设备配置 ················································································ 29 4.3 测试数据 ··········································································································· 30 4.3.1 企业内部IP电话之间的通话 ··································································· 30 4.3.2 企业IP电话与普通电话之间的通话 ······················································· 30 4.3.3 企业IP电话与市内电话之间的通话 ······················································· 31 4.4 企业内部电话会议 ··························································································· 31 4.4.1 添加会议房间 ···························································································· 31 4.4.2 管理会议房间 ···························································································· 32 第5章 总结与展望 ··········································································· 33 致谢 ······························································································· 34 参考文献 ························································································· 35 附录：外文文献原文·········································································· 36 外文译文 ························································································· 38
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第1章绪论
1.1 课题的研究背景
PSTN(Public Switched Telephone Network)，即公共交换电话网络，是一种以模拟技术为基础的全球语音通信电路交换网络。在两个地点进行通话时，PSTN将一条固定的线路被分配给对话的双方，这条线路虽然可能还存在多余频宽，却不能被其它用户所使用。
语音与数据综合业务的出现，给传统的电路交换技术提出了更高要求，PSTN这种基于电路交换的通信方式逐渐暴露出了其资源利用率低的缺陷。由于PSTN是一种电路交换的方式，一条通路自建立直至释放，其全部带宽仅能被通路两端的设备使用，即使他们之间并没有任何数据需要传送，因此这种电路交换的方式不能实现对网络带宽的充分利用。同时，由于缺少语音和数据的集成，以及模拟线路的低带宽，使得PSTN无法增强网络性能、无法提供附加的其他服务。
在这一背景下，以分组形式传送语音数据的VoIP（Voice Over IP）技术应运而生。
VoIP是在IP网络上进行语音通信，俗称IP电话。但现在的VoIP已不仅仅是指传统意义上的语音通信，而是指音频、视频、数据合一的实时多媒体通信。
语音网关类似于普通的程控交换机，目前语音网关都具备路由器和交换机的功能，可实现点对点免费通信，可以完全将语音通信集成到公司的数据网络中，从而建立能够连接分部在全球各地办公地点和员工的统一话音和数据网络。
IP融合通信是目前网络技术应用的一个重大发展方向，IP电话已经逐渐地代替传统电话机系统进入了当今的各大企业之中，相信在企业中也能得到应有的发展，它将是未来企业计算机网络发展的最大热点之一。
1.2 课题研究意义
传统电话（PSTN）相比，IP融合通信有以下优点：
1、通话费用低：VoIP技术最大限度的在可用传输链路上复用语音业务量，
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***计算机科学系毕业论文
这使得运营成本得以降低，通话费用也随之下降，尤其是长距离通信的费用。
2、节省带宽：传统PSTN电路交换电话消耗的带宽为64k，而VoIP的复用技术是在多个逻辑连接中动态的共享带宽，每个连接一般只需要6.16k。
3、体系结构开放： IP网络是一个开放的网络，这有利于多媒体业务的集成。VoIP网络可同时支持数据、语音、图像的传输，为将来提供全面的多媒体业务打下了基础，有利于多种通信方式的统一。
4、易于开发增值业务：VoIP网利用了Internet网的丰富资源和计算机的强大功能，可以灵活地控制连接、信令和数据传输，有利于各种增值业务的开发，如语音信息广播、语音邮件呼叫中心等。
以上优点使得VoIP技术迅猛发展。同时，相关的软件、硬件、协议和标准中的许多发展和技术突破，使得VoIP的广泛使用很快变成现实。这些领域中的技术进步和发展，为创建一个更有效、功能更强和互操作性更好的VoIP网络，起到了关键的作用。
对于企业用户来说，通过IP网关传送长途电话／传真，同样具有重要的意义：
1、节省长途电话费用
用IP网络完成所有话音／传真的传送，能极大地降低公司内部跨地域、跨国界的电话／传真成本。
2、减少设备投资
企业可以在原来只能传送数据的网络上获得增值的话音服务，而无需另外租用或者购买单独用于话音的设备和线路。由于所有内部通信(话音、数据、传真)均通过同一网络传送，企业可以大大降低购买和维护设备以及线路资源的费用。
1.3 课题研究的目标
为企业构建一个基于企业局域网的语音、视频通信平台。 1、 VoIP技术：VoIP技术产生的背景、原理、特点、发展趋势等。 2、 软交换技术：软交换技术产生的背景、概念、功能、意义、应用等。 3、 会话初始协议 (SIP)：SIP协议的背景、功能、网络元素、实现机制、SIP消
息的组成等。
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4、 会话描述协议(SDP)：SDP协议的概念、协议字段、应用等。 5、 实时传输协议(RTP)：RTP协议的概念、组成、协议字段、应用等。 6、 实时传输控制协议(RTCP)：RTCP协议的概念、组成、协议字段、应用等。 7、 测试环境搭建：企业融合通信平台的测试环境的搭建。
1.4 主要研究工作
本文分为两大部分，首先阐述了IP融合通信系统的一些基本理论，包括VoIP、软交换、SIP等。然后综合这些基础理论模拟一个企业融合通信系统的设计与实现的方案，争取方案能够在具体的企业中实现并为企业带来效益。最后对论文进行总结与展望，总结毕业设计过程中遇到的一些问题，以及如何去处理这些问题，讨论方案的进一步拓展。
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基于VoIP的企业融合通信系统的设计与实现毕业论文
