Hi Tarun,
Absolutely. SRST is possible with H.323.
Here is the link to the 'Cisco SRST 3.1 System Administrator Guide' it should give you most of the answers that you need...
http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_configuration_guide_book09186a00801f34d6.html
Below is a simple SRST config using 12.3 on a 3725
!
call-manager-fallback
secondary-dialtone 0
max-conferences 16
limit-dn 7940 1
limit-dn 7960 1
timeouts ringing 20
ip source-address 172.16.10.2 port 2000
max-ephones 12
max-dn 12
system message primary SRST V3.1 Operating!
dialplan-pattern 1 92317... extension-length 4 no-reg
default-destination 1000
access-code pri 0 direct-inward-dial
call-forward busy 1000
call-forward noan 1000 timeout 12
moh music-on-hold.au
date-format dd-mm-yy
!
Hope this helps.
