发展中的VoIP

1994年因特网商业化获得巨大成功。互联网采用网际互连协议IP在网络层进行互连,解决了异质网络的互通互连问题,为三网融合提供了技术基础。未来将发展统一的IP核心网提供综合业务,IP电话(VoIP)并不仅仅是在IP网上提供传统电话业务,未来IP电话将足传统电话智能网与互联网基于Web的应用的结合。用户可以通过各种网络接人在IP网上用软交换机进行交换。传统电话的交换和传输将逐步融入统一的IP核心网。     

综合移动智能网的建设原则

智能网是一个能够快速灵活地提供、生成和管理新业务的体系。其基本思想是将传统交换机的交换功能和业务控制功能相分离,在交换网上设置一些新的功能部件,原有交换机仅完成基本的接续功能,所有新业务的提供和控制都由这些功能部件协同原有交换机共同完成,是在原有通信网的基础上设置的一层叠加网络。由智能网提供、生成的一些新业务已经成为运营商们利润新的增长点,因而智能网已被电信运营商所接受。目前组建的智能网有:基于PSTN网组建的智能网、基于GSM网组建的智能网和基于CDMA网组建智能网。这三种网络相互独立,所开展的新业务也是…     

提升VoIP品质的一种语音处理系统

简介VoIP(IP电话)是一种使用IP协议为基本架构的语音传输系统。语音信号由此系统进行一连串的取样、压缩、打包,利用IP协议传输到另一个有相同IP协议的系统做反向的动作。VoIP软件提供使用者一个类似传统电话拨号的模式,但是实际上语音的传输完全不经由任何传统式电话的回路架构。除此之外,VoIP还提供所有一切网际网络所能提供的应用,例如:传递档案、程序计算、多方通信与会议、多媒体应用等。在实际应用时,对于每一个使用者而言,VoIP至少要提供如同使用传统电话一般的品质,另外还要能提供低价与多方应用的功能。为了使VoIP在外界…     

柯蓝电子新出《蓄电池维护管理方案》

近日,中国最大的通信制造业上市公司中兴通讯为新加坡知名运营商MobileOne承建的智能网系统实现正式商用,该系统将提供国际长途直拨电话预付费等系列增值业务。根据用户需求,此次新建的智能网系统包括了中兴通讯SCP业务控制平台、SMP业务管理平台、SSP业务交换平台等产品。该系统既为运营商提供了丰富的现实赢利模     

基于软交换的智能网与因特网互通技术

１前言公用交换电话网（PSTN）经过长期发展，已经能提供成熟、稳定的语音业务；特别是智能网技术的逐步完善，使PSTN提供丰富的增值业务成为现实。但是不容忽视的是，数据业务的比重已超过了语音业务，因特网在提供全球数据连接的同时，也为语音业务提供承载服务，即IP电话。IP电话的存在价值和竞争优势在于：它能将基于Web的新业务和传统电话智能网业务的优势结合起来，提供创新的综合业务，开拓广阔的新市场。实现IP网络的附加功能，不仅对发展企业的内线电话网络至关重要，也是扩大面向家庭市场VoIP服务的关键。下面主要分析因…     

短信业务在NGN网络中的应用

引言NGN网络是一个可以提供包括固定和移动话音、数据和视频业务等多种业务的分组网络。通信运营商为了充分利用已有的网络基础设施资源,采取将NGN技术与传统的电话交换技术、智能网技术、互联网技术、宽带接入技术有机地结合的策略,为用户提供传统业     

构建电信级的IP电话系统

华为公司设计的ＩＰ电话解决方案以运营商和企业用户为对象,提供高品质的服务、全方位的管理,吸收了传统电信业务的优点,是一个真正的电信级的全方位解决方案。ＱｕｉｄｗａｙＡ８０１０ＩＰ电话系统介绍华为ＱｕｉｄｕａｙＡ８０１０是一个多业务综合智能平台,可以实现ＩＰ电话、接入服务器、路由器、ＰＳＴＮ交换机以及智能网的组合功能。华为ＩＰ电话系统就是建立在该平台基础上的。ＱｕｉｄｕａｙＡ８０１０ＩＰ电话网关着眼于电信级大规模接入需求,将以其高性能、高可靠性的设计满足电信运营商、ＩＴＳＰ、企业网的需要。从协议上…     

基于智能网的移动小额支付系统

移动智能网在移动网中引入智能网概念,通过在现有移动网上逐步增加智能网相关功能模块,将业务控制功能从传统的交换功能中分离出来,使网络能快速、有效地生成和实现各种新业务。移动小额支付业务是由移动运营商、移动应用服务提供商和金融机构共同推出的一种移动数据增值业务应用,移动小额支付业务的开展可以基于运营支撑系统,也可以基于移动智能网,本文详细介绍了基于智能网的移动小额支付系统的系统方案、使用方式、支付方式及业务前景等。     

基于智能网的移动小额支付系统

移动智能网在移动网中引入智能网概念，通过在现有移动网上逐步增加智能网相关功能模块，将业务控制功能从传统的交换功能中分离出来，使网络能快速、有效地生成和实现各种新业务。移动小额支付业务是由移动运营商、移动应用服务提供商和金融机构共同推出，的一种移动数据增值业务应用，移动小额支付业务的开展可以基于运营支撑系统，也可以基于移动智能网，本详细介绍了基于智能网的移动小额支付系统的系统方案、使用方式、支付方式及业务前景等。     

提升VoIP品质的一种语音处理系统

简介 VoIP(IP电话)是一种使用IP协议为基本架构的语音传输系统.语音信号由此系统进行一连串的取样、压缩、打包,利用IP协议传输到另一个有相同IP协议的系统做反向的动作.VoIP软件提供使用者一个类似传统电话拨号的模式,但是实际上语音的传输完全不经由任何传统式电话的回路架构.除此之外,VoIP还提供所有一切网际网络所能提供的应用,例如:传递档案、程序计算、多方通信与会议、多媒体应用等.     

Seven myths about voice over IP

Voice over Internet Protocol (VoIP) is one of the fastest growing and most misunderstood technologies in the world at the moment. Confusion, outdated beliefs and urban mythology reign over such simple issues as how it works, the quality of the calls, and, of course, how much it costs. This paper examines seven existing myths about VoIP. These myths are that: (1) VoIP is free; (2) the only difference between VoIP and regular telephony is the price; (3) the quality of service isn't an issue nowadays because there's plenty of bandwidth in the network; (4) VoIP can't replace regular telephony because it still cannot guarantee quality of service; (5) VoIP is just another data application; (6) VoIP isn't secure; and (7) a phone is a phone is a phone.     

Vulnerability analysis and best practices for adopting IP telephony in critical infrastructure sectors

IP telephony has been rapidly introduced to replace the traditional circuit switched infrastructure for telephony services. This change has had an enormous impact on critical-infrastructure (CI) sectors, which are expected to become increasingly dependent on IP telephony services. Reliable and secure telephony service is a key concern confronting most organizations in the critical-infrastructure sector today. With the proliferation of voice over IP (VoIP) services in these organizations, it is important for them to understand the security vulnerabilities and come up with a set of best practices during the evolution of the IP telephony services. This article outlines the potential security issues faced by CI sectors as they transform their traditional phone systems into VoIP systems. Vulnerability analyses are conducted to understand the impact of VoIP security challenges in the new convergent network paradigm. The most common security measures are analyzed to identify their strengths and limitations in combating these new security challenges. A set of recommendations and best practices are offered to address the key issues of VoIP security as IP telephony is being introduced into critical infrastructure.     

VoIP mobility in IP/cellular network internetworking

This article explores VoIP mobility in the context of IP and cellular networks interworking. ITU-T Rec. H.323 gateways provide the interconnection between IP networks and switched circuit networks. They allow a call originating from an SCN phone to be transmitted over an IP network to an H.323 terminal, or bridged to another SCN phone. While H.323 provides interoperability with other SCN terminals, the major efforts have been focused on IP/wired SCN (PSTN, ISDN, etc.) interworking. In this article we discuss the challenges associated with the interworking between IP networks and cellular networks through H.323 gateways, and propose an innovative approach using the existing call transfer supplementary service to provide VoIP mobility in the H.323 IP telephony networks. The proposed approach uses existing components in the H.323 standard, thereby allowing VoIP mobility service in hybrid IP/cellular networks to be a value-added feature in the existing H.323-compliant Internet telephony systems     

Middleware 2007 Works in Progress

We propose a Web-service-based P2P architecture for VoIP called service-oriented VoIP. SOVoIP provides interoperability between protocols from both telephony and data networks using the converging behavior of Web services while ensuring security, extendability, and mobility. We also address other critical issues related to VoIP such as network address translation and firewall traversal, Enhanced 911, and the Communication Assistance for Law Enforcement Act. SOVoIP also provides modularity and reusability, making client development easier. Extendability in the Web service architecture is transparent to the client, so frequent client updates aren't required in order to consume new features. This reduces the time and money spent on upgrades.     

Mobile Internet telephony: mobility extension to H.323

This paper studies mobility extensions to ITU-T Rec. H.323 for the support of mobile Internet telephony. Internet telephony, also known as voice-over Internet protocol (IP) (VoIP), requires the transmission of two-way and real-time traffic over IP-based networks. The current version of H.323 allows IP telephony and the interoperability of the Internet with switched circuit networks (SCN). However, VoIP mobility has not been previously widely considered, where VoIP mobility refers to the mobility within the scope of IP telephony. We focus on terminal mobility for VoIP. We investigate the influence of mobility on the H.323 layer and propose an H.323 mobility solution to be implemented over the IP layer. Two approaches to mobility extensions to H.323 are described: using ad hoc multipoint conference expansion and using IP multicasting to emulate mobility. Besides, we have also shown that the proposed ad hoc expansion approach shares many properties with the alternative of using IP multicasting for mobility. Hence, the call signaling procedure for the ad hoc expansion approach is also applicable to the multicasting approach. Since ad hoc multipoint expansion has been defined in H.323, our solution introduces no additional entities to H.323 and requires minimal modifications to the existing H.323 protocol. Such mobility extensions can serve as a value-added feature for the Internet telephony systems compliant to the H.323 standard     

Analysis and Applications of Session Initiation Protocol (SIP) in Internet Telephony

1　Introduction　Internet telephony, also known as Voice over IP (VoIP)or IP telephony (IPtel), is the real time delivery of voice(and possibly other multimedia data types) between two ormore parties, across networks using the Internet protocols,and the exchange of information required to control this de livery. Internet telephony offers the opportunity to design aglobal multimedia communications system that may eventual ly replace the existing telephony infrastructure.　Internet Engine…     

基于SIP协议的IP电话语音系统设计与实现

本文基于SIP协议的IP电话作为主要研究内容,探讨了IP电话的相关议、相关标准和关键技术,对SIP电话协议进行了研究分析,设计提出一套结构合理的VoIP系统,并对系统组成、系统流程等作了详细的规划,安装配置OpenSER服务器,并能够使用MySql数据库系统来存储用户信息,基于分层设计的思想设计了客户端软件,最后利用该软件进行了系统测试,结果表明系统性能优良。     

VoIP网络电话技术及其应用

介绍了VoIP网络电话出现的背景产生及优势;讨论了VoIP通信网络的体系结构;研究了局域网PBX的体系结构及特征;分析了VoIP网络电话的信令协议;介绍了VoIP网络电话技术的应用及其特点。     

Steganalysis of transcoding steganography

Transcoding steganography (TranSteg) is a fairly new IP telephony steganographic method that functions by compressing overt (voice) data to make space for the steganogram by means of transcoding. It offers high steganographic bandwidth, retains good voice quality, and is generally harder to detect than other existing VoIP steganographic methods. In TranSteg, after the steganogram reaches the receiver, the hidden information is extracted, and the speech data is practically restored to what was originally sent. This is a huge advantage compared with other existing VoIP steganographic methods, where the hidden data can be extracted and removed, but the original data cannot be restored because it was previously erased due to a hidden data insertion process. In this paper, we address the issue of steganalysis of TranSteg. Various TranSteg scenarios and possibilities of warden(s) localization are analyzed with regards to the TranSteg detection. A novel steganalysis method based on Gaussian mixture models and mel-frequency cepstral coefficients was developed and tested for various overt/covert codec pairs in a single warden scenario with double transcoding. The proposed method allowed for efficient detection of some codec pairs (e.g., G.711/G.729), while some others remained more resistant to detection (e.g., iLBC/AMR).     

基于SIP协议的IP电话增值业务实现技术

讨论了SIP协议以及基于SIP协议的IP电话增值业务实现技术 ,并对SIPCGI、CPL、SIPServlets、JAINAPIs等几种SIP编程技术进行了分析与比较 ,归纳总结了开发IP电话增值业务的一般方法