Cannot Call an extension

I just setup a new asterisk on ubuntu with freepbx.

Setup Extensions 2000, 2001 and 2002

and Sip Trunk through my Voip provider through the 9

i can call an external line from 3 extensions (land line or mobile phone)
but i cannot call for one extension to the other

ip phones are online
extensions are in the same context

but i get the message

on xlite is written: call failed: decline …

the person you are callin is anavailable please try again.

Any Ideas?

Change permission to 777 in folder and files of


fixed the problem.