Featured Resources

Best VOIP Phone Services

SIP 101 - Session Initiation Protocol Explained

by Jim Sherman

Session Initiation Protocol or SIP refers specifically to a language that various computers can communicate to one another in so that they can complete voice calls. It has become vitally important in recent years as it plays a central role in VoIP or Voice Over Internet Protocol. VoIP Is the rapidly growing technology which has millions of Americans throwing out their local and long-distance telephone bills and replacing them with free calls made over the internet. While Session Initiation Protocol sounds like technobabble, it helps if you can imagine SIP as the common language that new generation operators use to complete calls over the internet. With SIP, however, the operators are no longer hundreds of people in a room somewhere connecting one call to another but simply your computer device connecting to the telephone or computer device of the person you want to talk to. The fact that there is no need for real operators, or even a central board to complete calls through, explains part of why SIP is so revolutionary. SIP was intended to give ordinary callers like you and me all the familiar functions and features of what we expect from a phone call, such as a dial tone, a ringing sound, etc. So while all the communication from our end seemed exactly the same as before, SIP makes phone calls by communicating directly with the other person’s telephone device. Unlike traditional telephony, which was based on a cog and wheel approach in which the call you placed goes through a central location and then is routed to the person you are trying to call, SIP is based on internet protocol. This means that there is no need for a central cog to run calls through, but rather calls can be made directly from person to person. The fact that the technology is based on internet protocol (IP) rather than a traditional cog and wheel also means that placing and receiving calls are no longer inhibited by location. To conceive of this more easily it is best to think of something like your e-mail. You can take your laptop and access your e-mail from your home, just as easily as you can plug that laptop into the internet at access your e-mail from anywhere. In the same way, you can plug your SIP phone into any access point in the internet and call a person who can be located anywhere in the world. Similarly you can receive phone calls from anywhere in the world no matter where you are, simply be plugging your SIP phone into the internet. As you can probably imagine, this ability has some pretty remarkable applications. For companies or businessmen that work out of the office, moving your office phone number is as simple as picking up the phone and carrying it with you. There is nothing else to it. For those often staying in hotels for travel or business, this means always having the direct office line with you wherever and whenever you want. No need to forward calls or even to ever pay for long distance or hotel phone access again! The SIP technology is already revolutionizing the way in which humans communicate. In recent years, literally millions of Americans have tossed aside their traditional land based phone lines and opted for the freedom and cheapness of VoIP. Empowered with SIP technology it is uniquely able to provide you with virtually free calling, anywhere in the world, anytime in the world, without having to forward calls, change your number, or rely on others to check important messages. It is truly a technology for the future of business as well as the future of communication. About the Author Jim Sherman writes about interesting topics such as SIP4PBX.

Security, Stability, and Interoperability Issues on VoIP Implementation

by Al Falaq Arsendatama

Now we have accepted that VoIP is no longer just a phone service, it has become feature rich as it merges with computer configurations. The VoIP's existence has changed considerably over the last few years, coupled with the availability of broadband connection to the Internet, plus leaps in multimedia technology in which virtual operations with remote sites becomes more enhanced, makes VoIP service a viable alternative to traditional communication offerings. Cost savings is not the only driving force for VoIP implementations, enterprises have to consider some business aspects that VoIP can bring about. VoIP creates potentials for applications that could not have been done before. Collaboration, integration, and interactivity between employees and applications are one of the several business benefits that enterprises can derive from VoIP adoption. Nevertheless, amid euphoria of VoIP technology, there are three important aspects to look at before a company goes VoIP. In the following paragraphs I will summarize the aspect of security, stability, and interoperability that play a key role in the successful implementation of VoIP. 1. Security VoIP implementations may expose new security risks and challenges that somehow become greater concern than quality and cost-efficiency among vendors and users. VoIP networks are vulnerable to all the same security risks as traditional IP data networks, including: Denial of Service (DoS), viruses, worms, Toll fraud and unauthorized access, Spoofing, and port scanning. It is recommended that organizations should adopt a layered, defense-in-depth security strategy to address the issue with the increasing proliferation of new Internet-borne attacks and malicious activities in recent years. In this architecture, the network is segmented into secure zones protected by layers of firewall, intrusion prevention, and other security services. This strategy allows the organizations to logically split and secure voice and data networks in front of individual voice and data components and between interactive points in the network. 2. Stability One of the main issues of VoIP is the amount of bandwidth required for each call. There must be adequate bandwidth reserved and the quality of the link must be well maintained throughout each call to ensure the users are not affected. As the very nature of VoIP call is real-time, any disruption during the call would be easily noticeable and unacceptable. The two issues that enterprises usually have to deal with here are bandwidth and quality of service (QoS). VoIP calls need a data transmission speed of 64kb/s to produce the quality of voice comparable to that of a normal telephone call. That 64kb/s channel needs to remain open and unaffected for the duration of the call. Theoretically, VoIP installations would not allow such a huge bandwidth to be allocated for VoIP alone. Therefore, there needs to be a compression taking place to compact the voice data into a considerable size before it gets transmitted over a packet switching network. G.723 codec that is incorporated in VoIP standard protocol H.232 can take a 64kb/s stream of data and squash it down to a mere 5.5kb/s or so. Generally, for VoIP to work reliably over WAN links, there has to be low jitter, low packet loss, a considerably high-speed connection between the endpoints, and less than 200ms delay. 3. Interoperability Compatibility between VoIP equipment from different vendors is a very important aspect to boost the use of VoIP products. Without standardized quality of service mechanisms businesses would need to buy all the equipment and the QoS server from the same manufacturer. The VoIP world seems to be divided between many vendors with reluctance to establish interoperability and some who are trying to be end-to-end supplier but at the same time worried about interoperability. The protocols used in VoIP communication are still considered fairly complex in comparison to most of the other protocols involved in Internet applications. SIP (Session Initiation Protocol - a signaling protocol for Internet conferencing, telephony, events notification, and instant messaging), that is regarded as simple and elegant the other protocols, is still not efficient. On the bright side, however, SIP is approaching status as an IETF (Internet Engineering Task Force) standard, after several years of work. With the recent version, it has achieved a greater amount of stability and changes are becoming smaller and smaller. Phone switch companies such as Nortel have recently begun supporting SIP, and now the manufacturers of handsets and related devices will soon ramp up their support. Motorola, Avaya, and Proxim have made collaboration on the creation and deployment of IP telephony solutions that will deliver new extents of communication mobility and network connectivity. With these three VoIP aspects covered, businesses will be able to maximize their investment by applying it as the backbone of internal communication such as phone conversation, videoconferencing, instant messaging, faxing, etc. Another area that will widely make use of VoIP is call centers, in which Web contacts, virtual operations with outsourcers overseas, and remote sites, such as home agents, all could improve the customer experience. New VoIP applications that we have not thought about may also come into existence as the services generates more business and profits for companies. About the Author Al Falaq Arsendatama is web entrepreneur specializing in technology and finance. Please visit DirecTV and Dish Network Comparison for free guide on selecting a satellite TV network.