In this small tutorial I will show you how to add a basic SIP extension to Asterisk using FreePBX. Extension are needed if you want to be able to make any calls with Asterisk.

1. 1. Open your browser and go to http://<your ip or hostname>/
2. 2. Click on "FreePBX Administration"
3. An popup will appear. Login with your FreePBX admin account. See next screenprint:
   
4. In the left menu click on "Extensions", see next:
   
5. You will now enter the "Add an Extension" page. Choose as device "Generic SIP Device" and click "Submit".
6. For a basic setup fill the next fields:
   - User Extension
   - Display name
   - secret
   - Enable voicemail if you want
   
   
   
7. Then ofcourse click on "Submit". Your basic SIP account now exists.

You can connect to this SIP account with a PC softphone like "3CX Phone" or using SipDroid on your Android phone and start calling. As long as you only add extensions you can only call internally (to other extensions). If you want to be able to make a call outside of your Asterisk server you need to add trunks and configure outgoing routes for these extensions to the trunk. I will create a article about this later on.