Enterprises today typically look at three communication links to the outside world. These are: leased line voice traffic connections to all other branch offices; voice gateway connecting the enterprise premises to the public network; and leased-line for Internet access.

Technology Options

n IP-VPN: It is an emulation of a private wide area network (WAN) facility using IP facilities, including the public Internet or private IP backbone. IP VPN can be either CPE-based or network-based. The primary advantage offered by IP VPN is that it provides a connectionless service in contrast to the layer-2 ATM and Frame Relay services and is a ubiquitous (any-to-any) service in contrast to point-to-point inherent feature of the ATM/Frame Relay service.

IP over VPN is the cheapest solution for corporates who do not want committed bandwidth. Service providers can commit only if the applications are mostly off-line and not time sensitive. Also, the security requirements are not of the highest order.

IP-VPN Services on Perception Scale
Advantages	Growth Drivers	Growth Inhibitors
Value-added services and applications	Total cost of ownership	Alternate services
Fully meshed topologies	Broadband access	Negative IP perceptions
Ease of adding/removing sites	Faster deployment	QoS and SLA concerns
Service Outsourcing	Expanding WAN market
Source: Frost & Sullivan

It also helps in effective utilization of bandwidth. One also has the advantage of automatic routing if the network is down for a particular route, which gives it an edge over other options. Since IP-VPN services can be delivered via the public Internet, a carrier can easily connect to an enterprise with its business partners anywhere across the globe.

n VoIP/Net Telephony: With effect from April 2002, the government has allowed ISPs to carry voice signals. The scope of the service includes PC-to-PC (within the country as well as abroad), PC-to-Phones (PC in India and phone abroad, IP-based H.323/SIP terminals in India to similar terminals both in India and abroad. Even the corporates can avail of Net telephony service through PC, IP phone, and analog phone, connected to an IP device. The cost of the IP device varies from $30 to $2,000, depending on the number of phones the corporate plans to connect to the IP device.

There are two ways in which one can deploy VoIP in enterprise. First, is to deploy IP telephony gateways to existing PBXs, which enable them to interface with IP phones and soft phones connected to local and remote LANs. This approach helps enterprises to protect much of their investment in digital and analog phones, and the corresponding line and trunk circuit cards. Second, is to deploy pure IP products and solutions and throwing away all the existing products.

As far as voice and data networks for the contact centers are concerned, the traditional circuit switch-based solutions are well proven in the market place and provide robust features and quality voice. However, IP-based converged voice and data platforms are better equipped to meet customer demands of consistency across all communications channels as it can facilitate voice and data interaction over a single network and a single platform. For instance, in a traditional environment, while a multi-location contact center would need ACD at every site, one ACD could suffice for all sites.

n IP-EPABX: IP-enabled EPABX is basically a circuit switch with an IP interface, while a pure IP EPABX is based on an IP platform. While both can enable VoIP, the former would permit a limited number of communication channels over IP and would require an intervening operator. Also, adding an IP line card into the EPABX shelf would offer no real advantage since all the drawbacks of the existing TDM platform of the EPABX, viz. limited scalability, high cost of integration and high administration and management costs remain.

On the other hand, a pure IP-based platform would incorporate RAS functionality and will allocate a unique IP address for each telephone, thereby permitting free and transparent connectivity with the IP world, with the need for an intervening operator. The key point here is that IP offers unlimited functionality and applications that an enterprise would surely need for achieving its business goals more efficiently and cost-effectively. For example, an IP EPABX would allow companies to do such things as video-conferencing and unified messaging from a single platform.