Electro/Telecom Industry Trends
A Look Inside TIA's TR41.4 IP Telephony Infrastructure and Internetworking Standards Committee with Chair Bob Bell
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Internet Protocol (IP) telephony - technology that basically uses the Internet to send data, voice, and video between two or more computer users in real time - has caught the world's attention. Dozens of companies have introduced products to commercialize the technology, and virtually every major telecommunications company has launched research to better understand this latest threat to their markets. As with most technologies, IP telephony and it's future lies in the hands of the people and standards behind it.
"When IP telephony originally got started everyone thought it was going to be an application that runs on the computer, but that's not where the vast majority of the work is being done. The Personal Computer (PC) just wouldn't work because most people turn them off at times, get busy in an application -affecting the PC's response time, and are just not comfortable talking into a microphone," comments Bob Bell, a Distinguished Member of the Technical Staff in Cisco Systems Enterprise Voice Video Business Unit and Telecommunications Industry Association's (TIA) Chair of TR41.4, IP Telephony.
Bell's involvement with TIA began three years ago. "TR-41.4, IP Telephony Infrastructure and Internetworking Standards, is part of Engineering Committee TR-41, User Premises Telecommunications Equipment Requirements," explains Bell. "TR41 has the responsibility for developing standards for customer premise equipment and our focus is on customer premise IP Telephony equipment." Some projects that TR-41.4 is currently working on include:
- Enhanced 911 Service
- Loss Plans and the Acoustical Characteristics of Voice over IP (VoIP) Telephony Systems
- IP Telephony Gateways
- Audio Transmission Levels
- Administration and Security Systems
- Minimum Requirements for Telephones or End Devices
There are numerous challenges in providing IP telephony access to the world. One of them is the ability to merge the installed base of users in traditional, cellular and Internet environments. "When you change a voice stream or media packet from the digital world to go out over analog trunk lines and to analog telephones, there are characteristics of the amplitude signal that you have to be able to put out on those trunk lines," explains Bell.
The IP world has some very specific quality of service (QoS) problems associated with it. Wide business deployment is still hindered by lower quality of voice over IP, particularly because of higher delay and jitter. "The IP telephone media packet has to go over an IP network and they don't go at an absolute constant rate. Even though they're transmitted at a constant rate, they go through routers and perhaps there's another packet on its way out of a router when yours comes in and you have to wait," explains Bell. "Things like this introduce delays and as the delays increase you get an echo," Bell continues. "Part of the recently published transmission standard, TIA-810, talks about delay and jitter and how to handle it."
An application problem of major importance to the Federal Communications Commission (FCC) and the IP industry is to improve the quality and reliability of 911 emergency services. It is vital that emergency services personnel are provided with information that will enable them to locate and provide assistance to users of IP telephony systems. The FCC has made it a requirement that cellular licensees, broadband Personal Communications Service (PCS) licensees, and certain Specialized Mobile Radio (SMR) licensees implement Enhanced 911 (E911) service. "You're supposed to be able to provide the Public Safety Answering Point (PSAP) with any information that will allow them to dispatch emergency responders that are able to go directly to that location, within 4000 square feet," Bell explains. "You don't want them on the second floor when the guy with the heart attack is on the third floor or you don't want a remote worker in Salt Lake to call 911 and have emergency response end up at headquarters in San Jose." TR41.4 will soon be introducing a draft standard that will address these challenges with two methods for identifying the caller's location. These are:
- The Co-network based solution mimics, to some extent, the existing Private Branch Exchange (PBX), whereby the telephone is connected to the IP switch by a cable in the wall and the IP switch knows in which port that telephone is connected.
- In the Beacon system, a set based solution, the telephone may be integrated with a Global Positioning System (GPS) receiver and the E911 call queries the GPS receiver to determine what it's X,Y coordinates are and transmits that location to the PSAP.
"Both approaches have problems," states Bell. "We're looking to other Standards Developing Organizations (SDOs) to assist with a workable solution. We try to work with and influence other SDOs, so if there are other standards in existence that are similar, we can pool resources and not recreate each others work."
To date, little has been done to standardize system functionality of IP-telephony infrastructures, but there has been extensive development of peripheral device standards for IP telephony systems in other SDO and industry forums such as the European Telecommunications Standards Institute (ETSI), Internet Engineering Task Force (IETF), Institute of Electrical and Electronic Engineers (IEEE) and the International Telecommunication Union (ITU). "Nobody is looking at IP Telephony as a systemic issue (e.g. How do I put a system together that provides all the functions I need?). TR41.4 is finding that this is an area where we can be a tremendous benefit to the industry," comments Bell.
An area that is coming to the forefront is security. It's important to determine how to design a network that has proper traffic engineering and that gets good response on the telephone, while keeping hackers from disrupting the telephone system. TR41.4 is creating standards to assist organizations in looking at the IP system logically to determine what areas within the system need to be segregated and providing the tools to help organizations segregate them. "We're looking at a network and dividing it into zones of control and zones of protection and determining what information flows should exist, if any, between various areas," says Bell. "If you have a centralized phone control system with a centralized call agent that handles your call traffic, you probably don't want that server to be directly connected to a network that has a direct connection to the Internet. Thus, making your corporate finance records available on the internet," he continues. "We're looking at the IP system from a generic point-of-view, not by looking at specific applications and hopefully by addressing security now, we will be able to help people, businesses and the industry have good solid systems."
It is widely accepted and acknowledged by the communications industry and industry analysts as a whole, that IP will become the universal transport of the future. SDOs are working fervently to make IP telephony a reality. "Right now IP telephony is in the wild and wooly west phase," Bell quips. "There will probably continue to be requirements for going out into the analog world for a while yet. We just have to plan the steps toward the future."
Bob Bell has been involved with the telecommunications industry for over 20 years and working with protocol telephony interfaces since 1995. His first contribution in the standards arena was with a group in the North American ISDN Users Forum (NAIUF) in 1985 - a group sponsored by the National Institute of Standards and Technology (NIST). At the same time, Bell was also working with the International Telecommunications Union (ITU) on the ITU H.323 standard - the umbrella standard covering signaling, real-time voice transports, codecs, etc.