"user name for authentication" field question


#1

Hallo
I wonder what is the purpose of field “user name for authentication”.
I think it can be treated as as string identyfying connectin channel between PBX and user.
It is independent from direction ( user calls user receives), it is for both direcetions this field will have the same value in NEW packet.
The question is whether I am right.
If not can you give me the example
Greetings