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| 7.4 |  | Cisco IP Telephony |
| 7.4.3 |  | Single-site model |

The single-site model has the following design characteristics:

- Single Cisco CallManager or Cisco CallManager cluster
- Maximum of 10,000 users per cluster
- Maximum of eight servers in a Cisco CallManager cluster (four servers for primary call processing, two for backup call processing, one database publisher, and one TFTP server)
- Maximum of 2,500 users registered with a Cisco CallManager at any time
- PSTN only for all external calls
- Digital signal processor (DSP) resources for conferencing
- Voice mail and unified messaging components
- G.711 codec for all IP phone calls (80 kbps of IP bandwidth per call, uncompressed)
- To guarantee voice quality, use Cisco LAN switches with a minimum of two queues