NBNCo Voice Call Infrastructure

The standard NBNCo customer device, known as a residential Network Terminal Unit (NTU-R) has 4 Ethernet data ports and two analog voice ports. The NTU replaces the existing broadband gateway. The two voice ports replace the previous twisted pair voice service connection, and are called Analog Telephony Adaptors (ATAs).

Subscribers connect their fixed line phone to one of the analog voice ports. If they have purchased a voice service from a Retail Service Provider, then the fixed line telephones will (appear) to work as before.

Each Analog Telephony Adaptor port provides the following:

  • electric power for handsets, conversion of analog voice signals to digital (and vice versa), DTMF tone conversion, dial tone, ring/busy signal, calling number display
  • a Session Initiation Protocol (SIP) Profile implementation. SIP is the standard signalling protocol for VOIP services

In addition to the analog voice ports, the subscriber NTU also has 4 data ports, similar to current broadband gateways. A voice service can also operate through a data port, using similar VOIP mechanisms to the ones on the analog voice ports. However, in this case the Analog Telephony Adaptor is a separate piece of equipment, which connects to the NTU data port. Engin currently offer VOIP services in a similar way, with an external “voicebox” connecting to a data port on the subscriber broadband gateway.

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