Today, we\u2019ll continue our discussion with observations from Ramesh Lakshmi-Ratan at VocalTec. Ramesh believes (and we concur) that one of the biggest reasons carriers are moving to IP-based telephony is that IP-based systems enjoy the same evolution interval as computing systems.Whereas TDM systems have historically provided evolutionary shifts in technology at five- and 10-year intervals, IP-based systems enjoy advances that follow Moore\u2019s Law - where processing capabilities double every 18 to 24 months. This represents a much shorter interval for increased efficiency and for creating new services that bring new revenue.Carrier network revenue structures have been built around differentiation between minutes of use AND the types of minutes. For example, wireline long distance may be priced at 3 cents per minute, wireless minutes may be priced at 8 cents per minute, and 800-number calls may be priced at 18 cents per minute. But the model for packet telephony is shifting how carriers price their services, from just basic minutes used to include connectivity and bandwidth capacity used.Carriers want to take advantage of the economics of IP telephony. But carriers must at the same time be able to accommodate shifting rate structures, migrating from minutes of use to access connectivity and bandwidth consumption. Call detail records (CDR) for carrier-to-carrier billing and traffic management must still be maintained regardless of the rate structures. At the same time, carriers must establish new technology models for interconnection that overcome any security concerns created by a more open architecture.Ramesh suggests one solution would be to use and improve on session border controllers already in use between the enterprise and the carrier. Session border controllers are purpose-built to prevent exposure of sensitive information between IP networks, yet the controllers can still provide information like CDRs for carrier billing.We believe that session border controllers will play an important role in supporting the shift in carrier networks. We also believe that added security measures will be required, and that carriers must take a hard look at their business practices and network management strategies if they want to enjoy full benefit from convergence-based networks.