FL-CME-SRST-5 On Cisco 2811 router

Unfortunately you can’t use this license FL-CME-SRST-5 on a Cisco2811 Router. You will need one of these. FL-SRST-25, FL-SRST-35, FL-SRST-50, up to 250 users. The minimum is 25 for the Cisco 2811.

http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps2169/data_sheet_c78-520521.html

This is a sad face for me :( I'm still planning to upgrade my 2811 at home to run CCME  and I'll need to buy some licenses to do this, looks like the start will be 25 though, rather than the 5 I wanted to start with.