Cisco Systems cannot claim to have invented IP-PBXs, but it certainly established the market for these systems by making IP telephony legitimate. Cisco's IP-based system is known as the Architecture for Voice, Video and Integrated Data (AVVID), and this product started shipping in mid-2000. Two years later Cisco claimed to have shipped 800,000 IP phones and, more impressively, to have equipped 6 million ports with power for IP phones.
Cisco's CallManager is the software-based call processing component of the IP telephony solution, extending features and functions to packet telephony devices such as IP phones, multimedia applications, and VoIP gateways. Additional data, voice, and video services, such as integrated messaging (the Unity product), multimedia conferencing, collaborative contact centers, and interactive response systems, may be linked with the IP-PBX through an open telephony API.
Cisco's CallManager is installed on a media convergence server (in the MCS 78xx series), which is a standard computer from manufacturers such as HP-Compaq, Dell, or IBM, with the exact specification set by Cisco and absolutely no applications other than telephony running in the MCS. Release 4.0 of CallManager can support up to 50,000 users and a conceptual network, with multiple voice servers, as illustrated in Figure 4.3. This software release also supports SIP, but Cisco believes that media gateway control protocol (MGCP) will be the protocol of choice within an enterprise for IP telephony.
Concerns about availability and reliability are addressed by using multiple servers, which may not be in the same location, and by having dual gateways to the WAN, which is not shown in Figure 1.
While the typical IP-PBX configuration is deconstructed into multiple components (communications server, LAN switch, trunk gateway to the PSTN, line gateways for digital and analog phones, and router to the IP-WAN), Cisco does have an all-in-one-box chassis-based CallManager 7750 system, for branch offices with from 50 to 250 users. There is also a 4225 system, for up to 20 users, serving phones and PCs, with a built-in data switch and router.
Cisco sells a number of models of desktop telephones—including the 7960 (6 lines), 7940 (4 lines), and 7910 (single line), together with an IP conference phone that was developed jointly with Polycom. Each of these phones includes a three-way switch, for 10- or 100-Mbps Ethernet connections, and can be dc-powered over the LAN from a Cisco distribution unit, situated in a telecom closet. The softphone product is good for collaborative working between PC users. Cisco was expected to have its own wireless phone, designed for the IEEE 802.11a standard, on the market in 2003, while wireless phones from Spectralink and Symbol, working to the 802.1 1b protocol, may be used with AWID.
For users to do their own system administration, such as call routing and screening, Cisco's Personal Assistant has speech recognition navigation with all its options linked to the class of service established for each user. Since an IP phone may be moved to any corporate network outlet, a report sponsored by Cisco and published by the Telecom Applications Research Alliance (TARA), in the spring of 2000 optimistically claimed that "the effort required for Moves, Adds and Changes is only 25% of that typical for a PBX of the same size."
We should note that Cisco's Unity voice mail system can connect simultaneously to CallManager and to legacy PBXs. On the other hand, it is still difficult to integrate between Unity and existing voice mail systems, so owners of Meridian Mail and Octel systems will need to replace these with the Cisco product, in those configurations where CallManager has been installed with TDM PBXs.
Cisco's well-known CEO, John Chambers, has been quoted as saying, "Data-voice-video integration is huge for us because it forces my customers to redo their networks," and this certainly appears to be coming true.
Cisco has signed agreements with several large service providers to support convergence of multiple networks with the AVVID solution, even while the users retain ownership of their systems. These situations may be classified as managed IP-PBXs and managed IP-Networks, but will not be the same as IP-Centrex.
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