If you're just doing it for yourself, and you're not already using Google Voice (GV) or have a Google user id to spare, you can get the 999 local number through GV, and then have it forward to your landline/cell. That's a little cheaper than Twilio.

For Twilio, I use a "Twimlbin" for each number, see below. An added benefit is that the callee (the outside person taking the call) always sees the same caller id, and so can put that in their address book with a suitable label.

Connectnetwork also has a protocol (a little more complex and finicky than unattended collect calls) which require the callee to press the right keys to accept the calls (or to reject them). I sometimes get that wrong (one out of three times) and sometime the system seems finicky (I thought I did it right, but it still treats me as if I rejected the call). So our prisoner knows to call a few times.

If this is still complex, hit me up on email (in profile) or comment here. I'd be happy to help.

  <?xml version="1.0" encoding="UTF-8"?>
  <Response>
  <Dial timeout="20" callerId="1999#######">
  <Number>+1444#######</Number>
  </Dial>
  </Response>