Here we will show Configuration process of Agent's extension in soft phone.
We have here shown configuration process of Zoiper

Click On option button

Click On add new SIP Account

Get User extension number, password and pbx server domain from your admin of pbx
Enter suitable name and press ok button it will create new account with test name.

Now Click to test account and enter PBX IP, User extension Details and password as shown in above image and press ok button

It will show Registered status on soft phone so your soft phone is ready to use.