March 11, 2002

N@C: What exactly is SIP?
Michael Frendo: SIP, or Session Initiation Protocol, is a Voice over IP signaling protocol that was adopted in early 1999 by the Internet Engineering Task Force (IETF).

N@C: Why is it important for service providers to have products that support SIP?
Michael Frendo: Simply put, SIP saves service providers time and money in the development and deployment of applications. With its foundation in Internet protocols, SIP enhances the ability to integrate voice features/capabilities with existing web-based services.

N@C: What are some other benefits of SIP?
Michael Frendo: SIP itself is simple; it's also very similar to HTTP, the core protocol for web browsers. So SIP is easy for implementers and programmers to learn and use. SIP was designed for distributed environments, so it is well suited for large carrier networks. SIP is a "lightweight" protocol, meaning the code does not require a lot of memory or processing power and can be implemented in a variety of simple endpoint devices, including phones and PDAs. Finally, SIP supports presence and mobility -- the growing expectation that any feature of a communications service should be available anywhere, anytime, while under the user's control.

N@C: Which call control and signaling protocol do you expect to be the long-term winner, H.323, MGCP or SIP?
Michael Frendo: That's a very common question. However, there is no single winner -- each protocol has emerged with its own place in the market. Currently, about 95% of all Voice over IP traffic is moving over H.323 networks. In addition, later versions of H.323 can scale to very large networks. MGCP (Media Gateway Control Protocol) is also being deployed in a large number of service providers, and is used by most "softswitches" to talk to a voice gateway. MGCP tends to be of greatest interest to traditional incumbent carriers. And SIP is designed to support a variety of packet-based services including voice and multimedia. So you see, there's customer demand for each protocol. I think we'll see H.323, MGCP, and SIP around for a long time, along with the need to interoperate between them

N@C: Can you quickly describe the Cisco SIP products introduced today and their roles?
Michael Frendo: We introduced the Cisco SIP Proxy Server, which acts as a "traffic cop," routing and managing SIP sessions across a network. It's a key SIP infrastructure component and provides an important base platform for application developers to build on. In addition, we introduced SIP support on telephony endpoints, including the Cisco IP phones and the ATA 186 analog telephone adapter. This means that the same Cisco end user devices can be used in both enterprise and service provider environments and will support a variety of call control and signaling protocols. We've also added support for SIP in the Cisco PIX firewall. Security is on everyone's minds these days and it's important to be able to provide secure SIP connections. Finally, we've enhanced the existing SIP support on Cisco's industry leading voice gateways, including the 1700, 2600, and 3600 routers and the AS5000 universal gateways. Our Cisco BTS 10200 softswitch and the PGW 2200 signaling gateway also support SIP.