OK thanks for the feed back try using Grandstream FXS gateway. I already work this out using Grandstream FXO and FXS.
So now i'm just trying this out using PRI.
Just an update, the linksys SPA-3102 works well, able to send and receive faxes to other fax machines and the 3cx fax server. We are only using it for outgoing, but we did get it to work for incoming as well.