Prerequisites

• Familiarity with configuring 3CX and administrative access
• A valid OnSIP Hosted PBX account
• An OnSIP Trunking enabled user

Step 1: Change SIP Address for Trunking User

You will need to change the SIP Address to match the Auth Username in the OnSIP Admin Portal User tab.  To do this, once logged into the Admin Portal, click on Trunking User to expand boxes:

• SIP Address (upper left) - modify
• Change first half of SIP Address to match Auth Username (exactly)
• Save

Step 2: Gather information for the OnSIP Trunking User

You will need the following information from the OnSIP Trunking User in the Admin portal:

• Username (this will be the same as the Auth Username since you've made the change in STEP1 above)
• Auth Username
• SIP Password
• Domain
• Outbound Proxy

You can find this information in the user detail pages under the Users tab in the Phone Configuration section.

Step 2: Add the OnSIP Trunking user as a SIP Trunk in 3CX

Log into the 3CX Admin page and go to General Tab.  Edit Trunking Details to look like below:

Step 3: Check for Registration

In OnSIP Admin Portal under the Trunking User, the Status will be "online" if you have a successful registration.