An IPmux-4 at each end of an IP network translates T-1 frames and signaling into IP packets, transmits these over an IP network, and then decodes and reassembles the complete T-1 signal at the other side of the IP network. As with classical T-1 equipment, the IPmux-4 accepts voice, data and video inputs, allowing true convergence at a cost of about $70 per equivalent DS-0-type channel.
Trend no. 2: Capacities on the rise
We asked vendors of gateways, gatekeepers/softswitches, and PSTN/central office replacement switches to delineate their products' maximum capacity in terms of concurrent channels supported (See "VoIP standards support, current and future," page 64). They detailed maximum configuration for a single-gateway chassis and multiple gateways that could be logically combined -- within an H.323 zone or MGCP domain. We also asked whether these products were targeted for enterprise or carrier/ISP environments.
The average maximum voice-over-IP channel density on a single-gateway chassis targeted to enterprise networks is 366 (based on 15 discrete systems). This represents a range of channel densities, from only 23 channels on Siemens' RG2500 up to 1,920 maximum on Clarent's Backbone High Density gateway. This average maximum represents a tripling of capacity in 1999 when the average maximum was just 100 channels per single-chassis gateway. Our research shows that about 90 percent of the phone systems installed in enterprise applications are 100 lines or less. So a tripling of capacity clearly addresses that part of the market. However, the remaining 10 percent of enterprise applications are way beyond that -- up to 15,000 lines and beyond are often in distributed applications. Many of the IP-enabled PBXs are addressing that higher end of the market, where they are more widely installed already.
On products targeted to carrier and ISP environments (15 discrete systems were included), the average maximum channel density is far higher -- 1,989 on average. This represents a range from 24 channels on Cisco's 3810, up to 15,000 on Lucents' Exchange Plus PSTN/central office replacement switch. This, too, represents more than a doubling of channel capacities from 1999. It's also notable that systems targeted primarily to the carrier market were not yet widely available in 1999.
We also asked vendors about their systems' ability to scale multiple gateways within an H.323 zone, which means they are under the control of the same voice-over-IP gatekeeper, or within a MGCP-based domain, meaning they are under control of the same call agent or softswitch. Enterprise products support 3,683 channels per zone or domain, while carrier systems average 10,950 channels.