Cisco.IP.Telephony.Planning.Design.Implementation.Operation.and.Optimization [Electronic resources] نسخه متنی

Networks Based on Cisco AVVID

Networks no longer are limited to performing toll-bypass call routing. Today, many networks are replacing the legacy PBX systems with IP-based call-processing servers; replacing legacy voice-mail systems with IP-based voice-mail systems; replacing legacy phones with IP phones; and replacing legacy video transmission with IP-based video transmission. This strategy is also the Cisco AVVID vision of truly converged voice, video, and data networks. In Cisco AVVID, IPT is one of the solutions. If three components of the legacy network previously shown in Figure 1-2 are replaced as described in the following list, the network evolves into the network shown in Figure 1-4:

Legacy PBXs are replaced by IP-based call-processing servers, such as Cisco CallManager

Legacy voice-mail systems are replaced by IP-based voice-mail systems such as Cisco Unity

Legacy phones are replaced by Cisco IP Phones

The migration shown in Figure 1-4 is a big change from a legacy network. These types of migrations have been done on hundreds of networks around the world. Several organizations currently run and manage true IP-based networks for their data and voice traffic or are in the process of migrating to IPT solutions.

Figure 1-5 shows the high-level network architecture of an organization that has transitioned to a Cisco IPT solution. The IPT solution replaced all the legacy PBXs, voice-mail systems, and phones with a true end-to-end IP-based solution. This network supports thousands of users located in different parts of world, using IP-based devices communicating over IP infrastructure. To reach this goal, you have to follow a structured approach; the rest of the chapters in this book discuss the use of PDIOO methodology to build such an end-to-end IP-based telephony network.