Virizon Interconnect problem

For past 2 weeks we are trying to interconnect with Virizon biz but having lots of problem.
They require IPsec for SIP, which we are not sure how to do it.
However with H323 they dont require anything, we have send couple of calls and non go through and contacted them and this is what we got back and we are really confused on how to go on about his, any help would be greatly appreciated

I really need some help with this one, anyone please?