2921 as an SRST router

[gp1200x]

I am confused on the router features on the 29xx and 39xx series. I have been able to take a 2951 SRST and reconfigure it as a CUBE when our 3945 died. Can I take any 2921 ISR router and turn it into an SRST router if I add a PVDM card and turn on the features?  Do all the 2921 ISR routers have PVDM slots?  Is making it into an SRST simply adding PVDM cards and accepting the LUA? 

[Richard Bradfield]

both the 2921 and 2951 have 3 PVDM slots, so no problem there, Only real difference is the number of SRST sessions 100 on 2921 and 250 on the 2951, usually a 100 sessions is enough. I think you have to pay for an SRST license though.