VoIP - Telecommunication of the future

Traditionally we are used to making phone calls over switched circuit networks. What this means is that dedicated "circuits" are required for calls and resource utilization is low, investment in infrastructure is high. This explains why we pay significantly for telephony - and specifically for long distance calls. As the world gets more and more hungry for information and there is increase in interaction between countries, the cost of communication over long distance becomes significantly high and disturbing. At the same time, the explosive growth of the Internet and its dramatically low cost for interaction across the Globe irrespective of distance has begun to show the power of packet networks, making the case for Voice over such packet networks.

It then makes sense to be able to use infrastructure that can support all media - data, voice and video. Wouldn't it be cool to use the same medium that uses e-mail, to send voice? If e-mail is so inexpensive why not have equally cheap telephony? The Internet works on well tested networks and protocols - TCP/IP being the most significant. VoIP - Voice over IP - intends to leverage the existing Internet for purposes of voice as well. It may not be as simple as it sounds - but the concept is now well supported by standards and infrastructure, which is beginning to make this a reality.

VoIP is beginning to make its presence felt, with several service providers beginning to deploy this technology enabling their customers to enjoy telephony at significantly low costs (ever tried Dial Pad?). Large corporations are using IP telephony to communicate between their offices spread across geographic locations (for those who are aware, we have IP phones here in MindTree conference rooms), thereby significantly cutting down communication costs.

Let us take a simplistic, high-level view of what VoIP exactly means. In a VoIP network, a telephone, a trunk circuit or a computer may be connected to a 'gateway', which converts the digital stream/analog voice to packets. These packets then travel over the Internet (or the Intranet, as the case may be) to the destination gateway - where the packets are decoded and converted back to digital stream/analog voice. This simply, is VoIP! Hmmm... wonder why so many companies are fighting to do something so simple! There are a few questions here -how is a call setup? Who controls the calls? Where do the dial tones come from? To know how the system operates, it is essential to become familiar with a few key components of the VoIP architecture.

First, there are the brawny, versatile yet dumb blocks called 'Media Gateways (MG)'. Gateways convert between streams/analog voice to packets, they do necessary encoding/decoding, they apply different tones on a connected telephone (or relevant tones/signals on digital trunks or computers), they open voice ports and then finally transfer data to the IP cloud. They are the 'window' to the IP network. A Computer, telephone or a trunk line is connected to a Gateway to enable this service (telephones are no longer the only devices to make calls-even your computer can function as a full fledged phone and EPABX all rolled into one).

But gateways are usually dumb (there is an exception if a gateway employs a particular protocol called SIP), they do nothing unless someone tells them to. It is the 'gateway controller' that actually controls the gateway and handles signaling. A controller (known as Media gateway Controller -MGC, or Call agent or Gatekeeper) is a piece of software that is capable of controlling several gateways. It is the controller which handles call setup, determines the target for a dialed digit/IP address (routing), keeps billing records, (though there are gateways who could do billing as well).

The MGC is the brain. Telephony is not limited to a simple phone call-what about conferencing? Call hold? Call forward? Voice mail? Interactive voice response? There are several applications that need to be supported, and the MGC manages this. In effect, the MGC is expected to completely replace the existing Switch. For this reason it's also called a soft switch!

There are currently four leading protocols that help in setting up these sessions and manage them (one could look at it as the MGC and MG using these protocols to provide the telephony services) they are H.323, SIP, MGCP and MEGACO. H.323 is ITU-T backed; it's a gorilla in size and complexity. SIP, MGCP, MEGACO are IETF backed -and are simpler and more suited to the Internet way of doing things (or so claimed by IETF!).

Opportunities
The VoIP area is vast and opportunities exist at several levels. Three core areas can be identified.

	Call Agent - development of a Call Agent that is redundant, extensible to handle several protocols, and provides for easy integration of other protocols. (A Call Agent may control several protocol end Gateways, e.g. H.323, MEGACO and a single Call Agent may support MGCP Gateways). The Call Agent needs to provide call control and routing, support different protocols, preferably be redundant, collect call statistics. In general it should support facilities a traditional switch may provide in the telephony network.
	Protocols - development of MGCP, MEGACO, SIP, H.323 and several other protocols used in this technology.
	IVR's (Interactive Voice Response Units) - providing several interactive services. And has a huge market.
	Application development that uses VoIP technology. This could be anything from VoIP enabled web sales centers, IP-PBX to Multi conferencing GUI

VoIP in the market
Seeing the vast potential in this convergence market there are several leading players that provide service and infrastructure at various levels. Note that the names of the companies is neither exhaustive nor specifically endorses their products, detailed lists are available on the net. (www.pulver.com or www.iptelephony.org may be a good place to look).

Infrastructure providers
The VoIP network has several components like Media Gateways, IP phones, Routers and Bridges. This equipment in turn may need DSP boards, packetizers, codec's and so on. Some of the vendors in this market are CISCO, 8x8, NMS, 3COM,Gordon Kapes, Lucent, Nortel.

Software element providers
Several components of the VoIP network are software driven. Companies specialize in developing the stacks, modules, integrate different components with a central Call Agent, development of billing software, O&M software etc. Some of the companies, which specialize in these areas, are Trillium, Catapult, Hughes, Tsemantics, Vovida, Portal, funk, Xybridge etc.

Integrators, consultants, network engineering consultants
These people help plan a deployment network and deal with engineering issues. They provide consultancy for choice of individual components and also help integrate the entire network -e.g. Telcordia.

Service providers
Provide the VoIP services to users. These people assemble or have the network assembled by integrators and then deploy them to the markets. e.g. Net2Phone, Dial pad, Microsoft.

Apart from those mentioned above there are several others in the market including big names like Siemens, Ericsson etc. The primary vendors may outsource development of certain components to others.

VoIP is here to stay, and is paving way for affordable telephony. As with any emerging technology, there are several problems. The QoS (Quality Of Service) is still not well guaranteed in the IP world, though there are protocols that are addressing this feature. The Internet is still cloggy and poses a challenge to high quality of voice, there are too many protocols competing with each other-leading to interoperability issues. But eventually, market dynamics will lead to stabilization and emergence of one or two leading standards that will be deployed. But very soon, you could chat with your near and dear ones without having to keep an anxious look at the meter!

Venugopal M. is a Technical Specialist for VoIP at MindTree.
He can be contacted at venugopalm@mindtree.com