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 App User tab.  To do this, once logged into the OnSIP App as Admin , click on the Trunking User to expand boxes:

• Under User Info, choose "edit info" and  change the SIP Address.
• Change first half of SIP Address to match Auth Username (exactly)
• "Save changes"

Step 2: Gather information for the OnSIP Trunking User

You will need the following information from the OnSIP Trunking User under Phone Settings:

• 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

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 App under the Trunking User, the Status will be "online" if you have a successful registration.