If you are going for 25 agents and going for dialogic based solution which is intel card then u need
one MSI 240/SC
one MSI 80/SC
two D300jct because generally we follow 2:3 ratio ie for 2 agents we need 3 trunk ports having voice capability
instead of D300 JCT which is E1 supported card u can use two D240 cards which ever is economical