Setting Up a 3CX Phone with Nextiva

A computer or mobile application like 3CX is a software program for making telephone calls over the Internet using a general-purpose computer, rather than dedicated hardware. Often, it is designed to behave like a traditional telephone, sometimes appearing as an image of a phone, with a display panel and buttons with which the user can interact. Utilizing a headset, rather than speakers and a separate microphone, will increase the quality of Internet calls with an application like 3CX.

The instructions below outline a two-step process to configure the 3CX computer application. The first step is to add a Generis SIP Device to the User who will be using 3CX. The second step will be entering the authentication details into the 3CX computer application. Please follow the instructions below to setup 3CX for a User.

If you have already configured the User with a Generic SIP Device, and have the authentication details, click here to jump to configuring 3CX.


Logging into NextOS and Adding a Generic SIP Device:


  1. Visit, and click Client Login to log in to NextOS.
  2. From the NextOS Home Page, select Voice
  3. From the Nextiva Voice Admin Dashboard, hover over Users and select Manage Users

Adding Generic SIP Device

Manage Users


  1. Hover your cursor over the User to whom you are assigning a device, and click the pencil icon that appears to the right of his or her name. 

Editing a Nextiva User

Editing a User


  1. Scroll down, and select the Device section. 

Nextiva Device Section

Device Section


  1. Select the Add Device radio button, then select Generic SIP Phone from the drop-down list below the Add Device list. 

Add Generic SIP Phone

Add Generic SIP


  1. Click the green Generate button under the Authentication Name text box.
  2. Select the Change Password checkbox under Domain.
  3. Select the green Generate button under the Change Password checkbox. 

Nextiva Generating Authentication Details

Generating Authentication Details


  1. Document the SIP Username, Domain, Authentication Name, and password onto a notepad, or in some way easiest for you to reference, as they will be important in setting up 3CX. 
  2. Select the Save button.  A pop-up message will appear indicating the device information has updated. 

Confirmation Message


Configuring 3CX:


  1. Open 3CX.  Upon opening 3CX for the first time, the 3CX Phone setup menu will appear advising that no SIP Profile is found.  Select Create Profile.  If 3CX has previously been opened, right-click the main screen and select Accounts

3CX Phone Setup

Create Profile and Accounts Options


  1. On the next screen, click New. 

Create New SIP

Create a New Profile


  1. Complete the following required information: 

3CX SIP Account Configuration Details

Account Configuration Details


  • Account Name:  A user-defined name for the account if multiple accounts are going to be configured in 3CX
  • Caller ID: If capable, this Caller ID information will be sent with outgoing phone calls
  • Extension: SIP Username or Line/Port
  • ID: Authentication Name
  • Password: Authentication Password
  • Select I am in the office – local IP under My Location and enter
  • All other fields are optional and should only be configured by an Administrator.  When completed, select OK. Then, select OK again on the Accounts window to register the account to Nextiva.


  1. Once 3CX uses the details entered to register to Nextiva’s service, there should be a message that states On Hook on the main screen. 

3CX On Hook

3CX On Hook


  1. Attempt to place a test call to ensure the setup is complete.
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