Register

Hi
I want to establish call between to SIP softphone on the LAN, Do i have to get register with the SIP provider also. Since all the call ringing, hookup ,connectivity is happening.but voice cannot get travel from one system to another system.
DO i have to get registered.Since in Xlite when iam right clicking it showing msg proxy register 192.168.1.46 :registered
Do i have to make changes in SIP.conf also