Hello Rob. Thanks for the quick info. thats not good, considering there are over 200 phones on site. Suppose its better to find out now.

Model of ISR is a 2811. Is that limited to 36? Seems like a strange cutoff. thx

Hey Pete,

Sorry man! These hardware based restrictions are very similar to the number of supported phones with CME and is probably a reflection of the available "horse power" on the box itself. The number on a 2811 is actually down to 35 with the newer IOS's. Here is the actual breakdown;

Cisco 880 SRST Series Integrated Services Router

Up to 4 phones

Cisco 1861 Integrated Services Router

Up to 8 phones

Cisco 2801 Integrated Services Router

Up to 25 phones

Cisco 2811 Integrated Services Router

Up to 35 phones

Cisco 2821 Integrated Services Router

Up to 50 phones

Cisco 2851 Integrated Services Router

Up to 100 phones

Cisco 3825 Integrated Services Router

Up to 350 phones

Cisco Catalyst® 6500 Series Communications Media Module (CMM)

Up to 480 phones

Cisco 3845 Integrated Services Router

Up to 730 phones

*The number of phones supported by SRST have been changed to multiples of 5 starting with Cisco IOS Software Release 12.4(15)T3.

From this excellent doc;

http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps2169/data_sheet_c78-485221.html

Hope this helps!

Rob