Introducing Blueworx Voice Response Voice over IP

This section introduces Voice over Internet Protocol (VoIP), and explains how VoIP works with Blueworx Voice Response for AIX.

This section contains the following sections:

What is Voice over IP?
Voice over IP is a set of protocols that allows you to perform telephony voice communications over a standard Ethernet IP network instead of over dedicated switched telephony voice channels and trunk circuits using ISDN or channel associated signaling.
How does Voice over IP work?
Voice and signaling are sent using standard TCP/IP protocols over a physical link such as an Ethernet network. This exchange of signaling and voice information takes place in both directions at the same time with each endpoint sending and receiving information over the IP network.
Components of a VoIP network
There are three main components of a VoIP network: user agents, gateways, and proxy servers.
Using VoIP with Blueworx Voice Response
The Voice over IP (SIP) feature for Blueworx Voice Response allows a Blueworx Voice Response application to act as an IP telephony User Agent (UA).
Overview of Voice over IP support
Voice over IP (specifically using the SIP signalling protocol) is implemented in Blueworx Voice Response using a SIP signalling stack, and one or more ‘adapters’ that transfer the voice data associated with A SIP call.
What is needed to support VoIP with Blueworx Voice Response
How many voice channels can a VoIP system support?
As with a PSTN Blueworx Voice Response telephony configuration, the number of channels available on each pSeries computer or BladeCenter computer depends on the number of adapters installed in the system unit.
Increasing the channel capacity of a Blueworx Voice Response T1 VoIP system by 25%
Compression
Blueworx Voice Response VoIP supports uncompressed data only over RTP streams.
SIP signaling
In a Blueworx Voice Response Voice over IP system, signaling information is sent and received through the AIX system unit LAN connection (usually Ethernet). This should be connected to an IP network such that all other SIP UAs (such as gateways, and phones) can contact each other over the network.
Application support
With Voice over IP, most inbound or outbound only applications will work unmodified. However, SIP capability can be further exploited if required (see Voice over IP tags).
What happens when Blueworx Voice Response receives a call?
When Blueworx Voice Response receives a call over Voice over IP, a specific sequence of events is followed:
How Blueworx Voice Response processes incoming SIP Invites
To determine the Called Party number, the To and Request headers are extracted from the message and processed as follows:
Outgoing SIP Invites
For outgoing SIP Invites, the process is as follows:
Outbound arbitrary SIP headers
The Blueworx Voice Response APIs can be used to specify headers and header data that are sent in certain outgoing SIP messages. This allows the state table, VXML and CCXML APIs to specify headers and associated values in outbound SIP messages: