SIP协议和H.323协议互通性研究

随着三网融合及通信技术的发展，实现SIP网络和H32网络之间的互通成为网络融合过程中一个亟待解的问题。对SIP和H323协议进行分析对比，并在此基础上提出互通模型，研究互通过程中的关键问题。     

SIP Trunk网关穿越NAT的研究

目前,企业内部大量部署的是支持SIP的IP-PBX,将计算机网和电话网集成在一起;NAT技术的出现,缓解了IP地址紧张的局面.通过NAT设备实现企业内部私网连接到公网.但NAT设备不能支持运用SIP协议的音频和视频的穿越,因此,实现SIP穿越NAT是一个迫在眉睫的难题.本方案中提出SIP Trunk网关技术,在不增加辅助设备的情况下,实现SIP协议成功的穿越NAT,节省了造价和维修成本.     

VOIP协议分析

VOIP是一种在Internet网络上进行语音通信的新业务。H.323、MGCP、Skype、H.248、SIP是VOIP的重要协议。本文在分析这些协议结构的基础上,研究和对比了各种VOIP协议的使用特点,为架构不同VOIP网络提出了协议选择建议。     

三网合一,沟通无限

联想传奇“三网合一”校园网站整体解决方案日前新鲜出炉 ,它融合学校外部网、内部网和无线网于一体 ,全面满足了学校对信息发布和沟通交流的需求。据介绍 ,它是在联想前期推出的针对学校 Internet网站 (外部网 )建设的传奇信息发布系统 4 .0基础上 ,融合了联想近期推出的具有无线通信 (无线网 )特色功能 ,可实现学校内部网 (intranet网站 )建设的传奇校校通应用集成平台 1 .0 ,从而实现三种不同网络合于一体。联想传奇“三网合一”校园网站解决方案的第一个“网”是指外部网 (Internet网 )。它充分融合了联想 FM36 5大型门户网站成熟的开…     

SIP协议在国家教育考试巡查系统编码设备中的设计与实现

本文根据<国家教育考试网上巡查系统技术规范标准>介绍了SIP协议在国家教育考试巡查系统中的应用.提出了SIP编码器的概念,并重点论述了SIP协议在国家教育考试巡查系统编码设备中的设计与实现.     

基于SIP协议的银行网络对讲监控系统设计与实现

基于会话初始协议（SessionInitialProtocol,SIP)设计网络通话系统以及挖掘SIP协议在一些专业领域的应用,是当前的一个研究热点。提出了SIP协议的一个新应用领域——银行网络对讲监控系统,设计了基于SIP协议的银行网络对讲监控系统解决方案,给出了系统设计架构图以及系统基本功能设计,并详细阐述了系统的硬件和软件实现方案。     

基于SIP协议的嵌入式VoIP网关设计

首先介绍了VoIP的基本原理及SIP协议的基本内容,然后基于STLC1502芯片,设计了VoIP网关的硬件电路,利用μClinux操作系统,实现了嵌人式VoIP网关的软件设计。     

基于广义随机Petri网的SIP的吞吐量性能研究

基于模型方法和软件仿真方法,对会话初始化协议（SIP）连接建立时的吞吐量进行了性能分析。首先在详细分析会话初始化协议（SIP）的服务工作过程的基础上,建立了SIP的广义随机Petri网模型（SPN）,利用工具SPNP6.0进行了模拟分析。考察协议建立会话过程中,网络建立连接请求数较少和连接请求压力较大时系统吞吐量的变化,从而可以针对不同的连接请求情况实施相应的SIP服务策略。     

一种基于SIP的VoIP语音通信系统的应用研究

由于SIP协议具有可扩展性、较为灵活、比较简单和易于实现等优点,将逐渐代替H.323协议,成为VoIP技术的核心协议,因而基于SIP的VoIP语音通信系统及其增值业务功能扩展的应用研究具有一定的现实意义。首先介绍了SIP和VoIP的基本概念和原理,然后设计了一个VoIP校园网络方案,最后通过实验对系统进行测试,系统测试结果表明该系统具有良好的应用前景。     

基于SIP的VoIP安全问题研究

当前,基于SIP的VoIP运用越来越广泛.本文介绍了基于SIP协议的VoIP工作原理,重点分析了基于SIP协议的VoIP所面临的安全威胁,并对可用于SIP协议的各种安全机制进行了研究.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.