In order to configure your Twilio, you have to register on the Twilio website. Then check, in the console view, what is your Account SID and token. This information is necessary to create the selected notification provider. You can register here. 

Adding a Twilio SMS Provider:

1. Log in as a user with the Jira Administrators global permission.
2. Choose the cog icon> Add-ons. Select SLA PowerBox > Notification Providers to open the SLA Notification Providers page.
   Tip: Keyboard shortcut: g + g + start typing notification providers...
3. Click the Add Provider button.  
4. Select SMS / REST API Gateway
5. Click the Next button.
6. Select the Twilio provider. 
7. Confirm with the Next button. 
8. Fill in all required fields which are listed and described below.
9. Save the changes with the Create button. 

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Configuration fields:

Provider Name - it is a Notification Provider display name and allows you to identify your notification.

Description - a short description of your notification.

Account SID - enter your Twilio account identification number.

Token - it is a Twilio token required for authorization. The authorization is based on your account SID and your token. This data can be accessed to when registering or checking Twilio account details.

Number from -  is the number

generated after the registration in the Twilio customer portal. 

User phone key -  is the name that uniquely identifies the user's phone number and has to be specified in: User Management > Edit User Properties > Add User Property.