To sign up for Textline with an existing Vonage (formerly Nexmo) number, we'll have you input your Vonage account information (Phone number, API Key, and API Secret), and then your Textline account will be created with your current Vonage number.
To create a new Department with an existing Vonage number, log into Textline and head to your Organization Settings by clicking the Settings > Departments tab, then click the New Department button.
Select Use a Nexmo Account, enter your Vonage/Nexmo account information, and then click Submit. A new Textline Department will be created with your existing Vonage number. This will not affect any voice functionality or any other current use cases for your Vonage number - it will simply route your text messages through our system.
If you are using your own Vonage number(s) with Textline, you will be paying Vonage for your messaging costs, not Textline. You will also need to complete Vonage's regulatory registration on their website.