Configure SIP Provider in Asterisk/Elastix

We have an Elastix PBX deployed in our testing environment. We have received demo accounts from two trunk providers ([login to view URL] and Broadvox) however we are unable to get the SIP trunks functional. Extension to Extension dialing is working as expected. We need someone to connect to our Elastix box and configure the SIP trunks for Broadvox (two extensions/DIDs) and [login to view URL] (one extension/DID). This is a new system that is not in production and is being used to test the call quality of SIP and VoIP in our location. X-Lite is being used as a softphone for right now.