VoIP
Diagram 1.1 Inbound call handshaking SIP protocol
Call path:
In this case DID provider is out of the public internet, sending the call directly to the PBX as it rings from the PSTN to a PRI circuit on theire side.
The advantage of this services is that you do not need to pay for the entire circuit plus the cross connect, instead you pay for one single DID which makes it way cheaper for small operators to have this kind of service and manage them at the long run.
Disadvantages: This runs over PUBLIC INTERNET so there is no service level agreement and the connection and quality of the connection are subject to best effort of both networks, the one originating and the one terminating the call as well as the hops in the middle which may take further degradation of quality.
Telarius PBX receives the call, plays an autoattendant based on time-of-the-day with message "DAY" or "NIGHT" depending on the time which has different purposes.
DAY-> Regular business hours all services available
NIGHT -> Office is closed directs to support, voicemail or direct dial the extension.
