Do I need a hardware card for OpenSS7?

Well, no. One of the objectives of providing the SIGTRAN and related protocols (see Where can I find more information on SIGTRAN? ) was to permit SS7 MTP and SCCP to be run on a Linux box which did not have any physical SS7 links attached to it. So, you do not need one of the SS7 link interface cards listed (see What hardware is supported?). All that you need is a Network Interface Card (NIC) capable of doing IP and you are in business: multiple SS7 nodes can be set up to communicate with each other using IP.