Content

| 7.4 |  | Cisco IP Telephony |
| 7.4.5 |  | Multiple sites with distributed call processing |

The multisite IP WAN with distributed call processing has the following design characteristics:

- Cisco CallManager or Cisco CallManager cluster at each location (10,000 users maximum per site)
- Cisco CallManager clusters are confined to a single campus and may not span the WAN
- IP WAN as the primary voice path between sites, with the PSTN as the secondary voice path
- Transparent use of the PSTN if the IP WAN is unavailable
- Cisco IOS gatekeeper for E.164 address resolution
- Cisco IOS gatekeeper for admission control to the IP WAN
- Maximum of 100 sites interconnected across the IP WAN using hub and spoke topologies
- Compressed voice calls supported across the IP WAN
- Single WAN codec supported
- DSP resources for conferencing and WAN transcoding at each site
- Voice mail and unified messaging components at each site
- Minimum bandwidth requirement for voice and data traffic is 56 kbps. For voice, interactive video, and data, the minimum requirement is 768 kbps. In each case, the bandwidth allocated to voice, video, and data should not exceed 75% of the total capacity
- Remote sites can use Cisco IOS as well as gateways based on the Skinny Gateway Protocol