Datacomm

March 6, 2003
Making the most out of VoIP

Rajesh Tuli

NEW DELHI -- VoIP is legal in India, but only for limited applications. Nevertheless, it will become a prime mode of communication. It will make long distance telephony cheap. It might even encourage the operators to change their switching platform to the ones that are IP compatible.

So far, IP telephony is possible using expensive IP telephones or by PC based solutions, which are expensive (the minimum price of an IP phone is around Rs. 2,000) as well. It cannot even replace the existing analog telephones that are inexpensive (the minimum price is around Rs. 300) in comparison. In its present form, IP telephony requires a separate network more akin with LAN networks using separate cabling. However, these two forms of telephony should integrate for usage in large organisations.

The right balance
Presently, data and circuit-switched voice networks are essentially independent units with limited interconnectivity. There is a great need to develop cost-effective systems that will carry voice and data over the same existing set of copper cables at speeds that will meet the requirements of data and voice communications within an organisation. A transparent intermix exists, because the transport cost of voice over data channels will be far less than its transport over dedicated circuit-switched channels. In an IP environment, multiple channels of communication can share the same bandwidth. However, in a circuit- switched environment, each communication channel requires dedicated bandwidth.

Advantages of circuit-switched environment
No one can ignore the circuit-switched environment. The vast availability of this legacy telecom network is a major attraction. In addition, the end customer premises equipment on these networks are affordable. It means that a telephone or a device to convert voice signal into a transportable form on circuit switches is much cheaper than their generic substitutes for doing the same on IP or data channels.

Circuit-switched networks have more advantages. They can offer better quality of service and continuity of similar telephone numbering plans. There is a great need to provide total integration of the two networks to take advantage of cheaper transport on the one hand and of cost effective end customer equipment like analog telephones, fax machines and answering machines on the other hand. This should be possible on the existing set of telephone wires with transparent interconnect with the circuit switched world.

The way out
The best way to do it is to provide integrated solutions for circuit and data switching needs of organisations, using just a single device. You just have to add an in-built VoIP card to support long distance communications over the Internet. These VoIP cards have powerful DSPs that help in voice compression, echo cancellation, comfort noise generation and packetisation.

These cards have in-built gateways and gatekeepers based on H.323. The gatekeeper software does the routing of voice packets to various destinations through the Internet. These VoIP cards can enable various applications like least cost routing (LCR), private networking and others. It is also possible to reach any extension user in the switch from any part of the world through the Internet. It is all about developing the packetising capability into the switch itself and using it as a shared resource. This brings down development costs.

The switch will essentially have the router capability. It will then allocate IP addresses to each analog and digital extension user to be able to integrate data switching and dynamic bandwidth allocation to the user extensions. Such router capabilities providing independent IDs can have additional advantages like setting up a pool of extensions for receiving fax, voice mail or modem calls.

Conclusion
All business houses will like to use VoIP as a preferred mode of communication for long distance telephony. This is the only integrated solution that does not require a separate data network for VoIP calls and allows usage of existing low cost analog telephony equipment for transparently receiving or making calls.

Alternative solutions are not only expensive, but also require separate data networks using PCs with multimedia kits or IP phones for voice communication. This makes the solution expensive and difficult to operate, as the user will have to make and receive calls from circuit-switched world on separate telephones. Moreover, the solution should be intelligent enough to automatically route certain calls over IP networks and others over circuit-switched channels.

(The author is the CEO of Coral Telecom)