SRND is always the place to look

AC Performance and Capacity

The Cisco AC application supports the following capacities:

•Maximum of 500 attendants per cluster.

•Maximum of 500 pilot points per cluster.

•Maximum of 125 attendant and pilot point pairs per Cisco MCS-7845 server

•Maximum of 100 attendant and pilot point pairs per Cisco MCS-7835 server

•Maximum of 75 attendant and pilot point pairs per Cisco MCS-7825 server

•The Cisco MCS-7845 server supports a maximum of 1250 AC devices.

•The Cisco MCS-7835 server supports a maximum of 1000 AC devices.

•The Cisco MCS-7825 server supports a maximum of 750 AC devices.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/apps.html#wp1044311

More info available in the link

HTH

java

if this helps, please rate