In FreePBX, click on Trunks.
Then click on Add SIP trunk.
Enter the phone number in the Outbound Caller ID box.
Enter two in the box for Maximum channels.
In the Trunk Name box you enter in callcentric
In the PEER Details you would enter:
Important, the username is the customer number that Callcentric gives you. It starts with 1777 and has seven more digits. The password is the one you used when you set up the account.
Now enter the Registration String at the bottom of the page.
Now to add an Inbound Route:
Click on Inbound Routes. Click on Add Incoming Route.
Enter your customer number in the DID Number box.
Next set the destination:
Have it go to an extension, a ring group, a recording, or the conference.
Hit the Submit button.
Last, click on the red bar to Apply Configuration Changes.
So far I have not used Callcentric for outgoing calls and I will try to set this up later.