The from_user option would be set on the endpoint used to the dial the remote side. It sets the user portion of the From header, commonly required for ITSPs and when connecting to other Asterisk instances when doing username/password authentication.
It avoids abusing caller ID for the account name, and allows PAI or RPID to be used to send a caller ID that is not the same as the account name.
There does seem a tendency for FreePBX users to over from-user and manipulate the caller ID, but that is probably because FreePBX doesn’t expose users to the true SIP URIs so they don’t really understand the significance of the from user.
oh then you guys are suggesting this method in case my account name is different from the CallerID i want to send! THAT IS WHAT I UNDERSTOOD. is it right @david551 ?
but in my case i just want to send the CALLERID which is the same as account name.