Content

| 7.4 |  | Cisco IP Telephony |
| 7.4.2 |  | Cisco IP telephony designs |

Design Models
The overall goals of an IP telephony network are as follows:

- End-to-end IP telephony
- IP WAN as the primary voice path with the Public Switched Telephone Network (PSTN) as the secondary voice path between sites
- Lower total cost of ownership with greater flexibility
- Enabling of new applications

Currently, there are four general design models that apply to the majority of implementations:

- Single-Site Model
- Multiple Sites with Independent Call Processing
- Multisite IP WAN with Distributed Call Processing
- Multisite IP WAN with Centralized Call Processing

The following sections summarize the design goals and implementation guidelines for each of these models.