The Versatility of Dialogic HMP

By Sean White, Pronexus Telecom Support Engineer

When planning and ultimately deploying an IVR solution you will need to decide how the IVR will connect to the telephony infrastructure.  This means that you must decide  what  protocol to use and what hardware is needed for the server to support that protocol.  Often, customer sites may have stipulations on how your IVR can connect to the existing telephony infrastructure, since the IVR will be on their site after all.  Then there are the times when you get to decide.

So, where to begin?  Considerations are seemingly endless; protocol support, hardware requirements for the interface, server requirements, channel density and performance, life expectancy of the interface, cost, ease of integration, application performance on a given protocol.… just to name a few.

An IVR built with VBVoice can work with T1/E1 ISDN or CAS, analog, and VoIP through integration with Dialogic media.  In the case of T1/E1 and analog, a PCI or PCI-express board is installed on the server, and specific drivers are installed.  Some configuration on the board and on VBVoice is required, but the integration is relatively straightforward.  In the case of using media boards from the Dialogic JCT and DM3 family, all resources are hardware-based.  This means the DSP (to perform all voice processing like detecting DTMF, conferencing, fax, echo cancelling) is on the board and there are limited ways to configure resources.  Adding more resources might require adding new cards to the server.. Depending on what the production system will do, you must evaluate the different boards that are available to get the one you need in order to get the required density and allow for eventual expansion in the future .  When you consider that these boards are full length PCI format (12.5 inches long and 3.5 inches tall) it can become a problem to find a server chassis to accommodate the boards. In a scenario where the IVR must reside at the customer site, the footprint of the server can become a potential issue when having to ‘fit in’ to the existing server-room layout.

We are seeing an increase in the number of VoIP IVR deployments.  Given the versatility, lower cost, and excellent performance characteristics of VoIP, as such I will focus more on this protocol integration.

Dialogic Host Media Processing (named now DialogicPowerMedia HMP) performs media processing without requiring the use of specialized hardware, using the server’s CPU instead.

HMP, as it is more commonly referred to, is able to do call control and media processing for TDM cards like  Dialogic’s lineup of DNI boards for E1/T1 or could be used for a full VoIP solution. For VoIP it handles both the SIP/H.323  call stack and media processing.  Also, it is possible to run a T1/E1 solution with VoIP capabilities by using a DNI board; which offers capabilities for  creating media gateways with complex scenarios, interfacing TDM and VoIP with powerful media processing.

HMP works like this: all call processing is handled by the local CPU.  The physical VoIP connection is the primary NIC card of the server. What determines the number of VoIP channels available is in the HMP licensing.  For each VoIP channel (SIP or H323) there must be 1 RTP, 1 IP Call Control, and 1 Voice resource, which is achieved by purchasing the corresponding HMP license.  If you must handle fax capabilities, then you will need to add to this a fax license.  If you need Conference, then you will need to add a Conference license for each Conference member that there will be. The licenses determine the resources or capabilities of the VoIP call stack.

Since there is no PCI or PCI-express board required in a VoIP scenario, the server chassis doesn’t need to be large in order to physically fit the board.  A 1U chassis could be used to run the IVR, for example.  With the latest version of VBVoice and Dialogic HMP, it is now possible to deploy the IVR solution on a Virtual Machine, greatly increasing the versatility of the solution.  System performance is very stable.  Modern server specs allow the IVR to handle 200 concurrent channels where an efficient application is using pre-recorded prompts, DTMF handling and database queries.  This number decreases with the addition of Text To Speech and Speech Recognition of course.

One of the great aspects of the HMP VoIP solution is that you only purchase the resources you need and when you need, allowing an easy extension of capabilities of your application without the need for hardware changes. This offers huge cost savings when compared to a PCI or PCI-express media board solution. With the boards, as mentioned, the resources are hardware-based.  So, you may be purchasing a board which has capabilities that your IVR won’t use, such as a DMV board with fax capabilities.  If your IVR will not perform fax, then why have fax resources available?  You have paid for this ability, but won’t use it, so this is money lost.

With HMP you purchase the licenses which equate to resources.  So, you have 4 RTP, 4 IP Call Control and 4 Voice licenses for HMP.  This means your IVR can handle 4 VoIP channels.  As production rolls along, you find it necessary to increase the number of channels which the IVR can handle.  It is just a matter of purchasing additional licenses to increase capacity.  If you need 4 additional channels, you would purchase another 4 RTP, 4 IP Call Control, and 4 Voice.  The new license is combined with the existing one to create a block of 8 RTP, 8 IP Call Control, 8 Conference.  These resources are pooled, and are available to any of the application’s channels.

If your existing infrastructure will allow for a VoIP connection, or you have the option to connect the IVR to a VoIP provider directly (maybe your ISP provides a VoIP connection), then implementing an HMP VoIP solution is a great option.