Technology

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02/09/04

Definition

VoIP stands for 'V'oice 'o'ver 'I'nternet 'P'rotocol. VoIP is the ability to make telephone calls and send faxes over IP-based data networks with a suitable quality of service and superior cost/benefit.

Background

There was no Internet about 20-30 years ago. Thus, the only source of interactive communication was telephone at PSTN line cost. Data exchange was quite expensive, especially for a long distance. Internet has allowed people to communicate with each other by using new services like email, chat etc. Today, Internet is being used for various purposes like exchanging data (like images, sounds, documents) and talk to each other using applications like NetMeeting, Internet phone and different types of messaging services (Carden).

Introduction

Voice over IP allows companies to provide long distance phone services that are usable, very affordable and of good quality. Although most of these phone services utilize the Internet, the consumers need not have a computer, or an Internet connection, or even realize that they are talking through the internet (Sirius). VoIP converts voice in data packets from analog to digital, sends them and reconverts then in voice at destination.

How It Works?

VoIP technology uses packet-switching method to provide several advantages over the traditional method of circuit switching. For example, packet switching allows several telephone calls to occupy the amount of space occupied by only one in a circuit-switched network. This gives businesses a competitive advantage in customer support. How it works is that the sending computer splits data into small packets, with an address on each one telling the network where to send them. When the packets are receiver by the computer, it reassembles them into original data.

Packet switching is very efficient. It minimizes the time that a connection maintained between two systems. It also frees up the two computers communicating with each other, so they can accept data from other computers (Tyson).

IP Telephony Solution source: Network computing magazine

Standard Protocols

There are two major types of standard protocols used for VoIP. For a quick comparison click here.

	H.323
	Session Initiation Protocol (SIP)

H.323

H.323 is a standard created by the International Telecommunications Union (ITU). H.323 is comprehensive and a very complex protocol. It provides specifications for real-time, videoconferencing, data sharing and audio applications such as IP Telephony.

SIP

SIP is a much more streamlined protocol and developed specifically for IP Telephony. It is smaller and more efficient than H.323. SIP takes advantage of existing protocols to handle certain parts of the process. An example would be of Media Gateway Control Protocol (MGCP) that is used to establish a gateway connecting to the PSTN system.

Estimated Costs

VoIP product pricing is available from Nortel Networks and Cisco (Carson, Davis):

Nortel Networks

(1) Nortel Connection Manager $15,000

(1) Passport 4460 Gateway $ 8,000

(25) IP Enabled phones $ 8750 $ 350 for each.

Total (list pricing) $31,750

Cisco

(1) 7 830 with Call Manager $14,995

(25) 30 VIP (high-end) hard phones $15,495 $ 609.80 for each.

(1) Digital interface to legacy PBX $10,000

Total (list) $40,490

Advantages of VoIP

	Cost reduction - There can be real savings in long distance telephone costs which is extremely important to most companies, especially companies with international markets. It can provide competitive alternative to PSTN networks.
	Simplification - An integrated voice/data network allows more standardization and reduces total equipment needs. An example would of what HPU is trying to do in the future.
	Consolidation - The ability to eliminate points of failure, consolidating accounting systems and integrating operations can be very efficient.
	Advanced Applications - The long run benefits of VoIP include support for multimedia and multiservice applications, something which today's telephone system can't compete with.

Potential Risks

Voice quality - Quality of service is low sometimes. The technology has not been developed yet to replace the quality and service of PSTN yet.

Reliability - Data networks are not as reliable as voice networks because what if the network goes down. This problem rarely happens with other telephone carriers.

Delay - Echo and talker overlap.

Packet Loss - IP networks cannot provide a guarantee that packets will be delivered in order and there is a possibility of packet loss.

References

Cardan, Philip. (May 8, 2000). Building Voice over IP. Network Design Manual. Retrieved on October 21st, 2002 from: http://www.networkcomputing.com/netdesign/1109voipfull.html

Carlson, D. Davis, B et al. Voice over IP Product and Pricing Overview. Net@EDU. (October, 1999). Retrieved on November 2nd, 2002 from: http://www.educause.edu/netatedu/groups/ics/carlson-davis.doc

Tyson, Jeff. (2000, June 14). How IP Telephony Works? http://www.howstuffworks.com/iptelephony.htm

Voice over Frame Relay. (2000). Retrieved October 29th, 2002 from: http://www.protocols.com/voip.htm

Voice over Internet Protocol. Dancom Online Services. Telecom Tutorials. Retrieved November 2nd, 2002 from:

http://www.excellence.com.pk/it/voip/

What is VoIP? (2001). Sirius Technologies. Retrieved October 30th, 2002 from:

http://www.voipinfo.com

This site was last updated 11/01/03