Interoperability with IP-PBX or VoIP Providers

All opinions and information are solely the opinions of Pronexus. When setting up your interactive voice response (IVR) please make sure to contact your private branch exchange (PBX) or voice over internet protocol (VoIP) provider for their recommendations.

PBX Interoperability

There is no specific configuration requirement needed for connecting the VBVoice/HMP IVR with a local PBX or VoIP provider. The expectation is that the PBX or VoIP provider will support session initiation protocol (SIP) standard. The IVR can connect to a SIP trunk or to a SIP extension (also called SIP agent).  The IVR behaves as a user agent with multiple channels, where the number of channels is determined on the IVR by the number of host media processing (HMP) and VBVoice licenses. The PBX or VoIP provider is simply providing the bandwidth connection for the IVR to send/receive calls.

PBX and VoIP Integration Basics

Once you install VBVoice and the Dialogic HMP driver on the VoIP IVR system, the VBVoice Interface Installer should run to select the Dialogic HMP card type. This enables the VoIP capabilities of VBVoice applications. VBVoice (with Dialogic HMP) supports H323 and SIP protocols. We always recommend that customers use SIP due to its general ease of interoperability between different endpoints and widespread usage.

When integrating with a customer site PBX or with a VoIP carrier, VBVoice has some basic pre-configurations. The following is based on a SIP setup:

  1. The default codec negotiation for VBVoice is to use G711.  Enhanced real-time transport protocol (RTP) licenses can be purchased to use G723 or G729
  2. By default, VBVoice is configured to use u-law.  We also support a-law with a minor configuration change in the vbvoice.ini file
  3. By default, the VBVoice IVR will accept both RFC2833 DTMF (touchtone) and inband dual tone multi-frequency (DTMF) methods.  This can be configured to be explicitly one or the other as may be required for reliable DTMF delivery
  4. For SIP signaling, the supported transfer type is SIP REFER
  5. Bandwidth consumption for SIP is 87 kb/s up and 87 kb/s down

SIP Registration

If the VBVoice/HMP IVR is required to register to the local PBX or VoIP provider, configuration entries must be added to the VBVoice software. This can be done directly in the vbvoice.ini configuration file (Start>Run>vbvoice.ini) or via the VBVConfig utility.

The two supported options are:

  1. Registration WITHOUT authentication
  2. Registration WITH authentication (also called MD5 Digest Authentication)

The required entries to have the VBVoice/HMP IVR register WITHOUT authentication are:

RegServerIP - IP or a domain name of the proxy server

RegEndPointIP - Account to be used on the proxy

RegTerminalAlias - Username and IP of machine running VBVoice

RegTimeToLive - Time-to-live for the registration in seconds (When this expires, VBVoice will automatically retry to register with the proxy)

The required entries to have the VBVoice/HMP IVR register WITH authentication are:

RegServerIP - IP or a domain name of the proxy server

RegEndPointIP - Account to be used on the proxy

RegTerminalAlias - Username and IP of machine running VBVoice

RegTimeToLive - Time-to-live for the registration in seconds (When expires, VBVoice will automatically retry to register with the proxy)

SipAuthenticationRealm - domain part of the authentication triplet (optional)

SipAuthenticationUsername - user name (optional)

SipAuthenticationPassword - password (optional)

An example of the VoIP entries for SIP registration is outlined below:

[VoIP]

RegProtocol=SIP

RegServerIP=proxy.example.org.

RegEndPointIP=hmp@proxy.example.org

RegTerminalAlias=hmp@192.168.1.1

SipAuthenticationRealm=proxy.example.org

SipAuthenticationUsername=hmp

SipAuthenticationPassword=pronexus

Connectivity Testing and Packet Tracing

When looking to evaluate a new SIP installation we install a packet analyzer tool. (We use WireShark, available for free download.)

With the packet analyzer tool installed we can clearly see the IVR perform SIP registration. We can also analyze test calls to ensure that audio quality, touch tone and call transfers are working as expected.  

All opinions and information are solely the opinions of Pronexus. When setting up your interactive voice response (IVR) please make sure to contact your private branch exchange (PBX) or voice over internet protocol (VoIP) provider for their recommendations.
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