SBC 30 calls setup question



I use Cisco 4331 voice gateway with SIP trunk. Then I use another SIP trunk from 4331 to Call Manager.
There is no firewall between 4331 and SIP provider, just ACL. Can I still use SBC and place between SIP provider and 4331 voice gateway? I see from some videos its usually place between firewall and PBX.
Lastly is it hard to setup?

Thank you