SARK V4.0.0 Callback
CALLBACK
SARK Callback provides a secure DISA (Direct Inward System Access) type facility. DISA is designed to allow external users to dial into the PBX and receive dial-tone so they can dial out and have the onward call charged to the PBX. Obviously, such a service could be abused if it were offered without some kind of security. Traditionally this has involved the use of a password or PIN and SARK has a feature like this.
Callback is a little different. How it works is this; a user calls into the a nominated "callback" DDI. The call is ended immediately by the PBX without ever going off-hook. The PBX then looks up the CLID of the caller in an authorized list and, if it appears, calls back to the same phone and gives the caller dial-tone. This is quite a secure feature because it can only ever give dial-tone to authorised CLIs and it also carries ALL of the cost including the leg back to the original caller.
set-up
First of all you need to nominate an inbound trunk or DDI as a callback trunk (you can have as many as you like); you simply create a DDI and choose 'CALLBACK' from the route dropdown.
Now you can set up your authorized user list; you could have done this before setting up your trunks, the two are not interdependent. Choose callback from the features menu tab and click the new object button at the top right of the screen.