I am using freepbx, I have a voip account which i use in zoiper, can use it in SIP trunking to getting call and automated it. Please help if yes then about the authentication and all that. In zoiper to make call i just added my authentication username outbound address and SIP server and it worked please help how to do same in freepbx.
SIP does not have concepts of trunk and extension. An account configured for use with a phone would almost always be outbound authorisation, outbound registration, from the user point of view, as is FreePBX, from an “extension”'s point of view. It may be restricted to one call at a time, so not really a trunk.