3.1. Voice Features Supported

The PBX Integration board uses a dual-processor architecture comprising a DSP (Digital Signal Processor) and a general purpose microprocessor to handle all voice processing functions. This dual processor approach off loads many low-level decision making tasks from the host computer.

When a PBX Integration system is initialized, firmware is downloaded from the host PC to the firmware RAM and DSP memory on the PBX Integration board. This downloadable firmware gives the board all of its intelligence and enables easy feature enhancement and upgrades. Based on this, the PBX Integration board can perform the following operations on incoming calls:

• automatically control the volume of the incoming audio signal
• record and compress the incoming audio voice signal. Sampling rates and coding methods are selectable on a channel by channel basis
• detect the presence of tones - DTMF, MF, or an application defined signal or dual tone
• perform call progress analysis (CPA) to determine the state of an incoming call.

  NOTE:

  PBX Integration boards only support CPA when used in the default routing configuration. For instance, if a voice resource of a D/82JCT-U is listening to a front end other than the default (its own), it may return a disconnected result. This is because these boards support the call progress analysis feature of dx_dial( ), only when a board is using the default TDM routing. In other words, PBX Integration board voice resources cannot be used to provide CPA capability for other boards.

For outbound calls, the PBX Integration board can perform the following:

• play stored compressed audio files
• adjust the volume and speed of playback upon application or user request
• generate tones - DTMF, MF, or an application defined signal or dual tone.

The PBX Integration board is basically a D/41D board with specialized PBX circuitry replacing the analog front end. The PBX Integration board performs features available on a D/41D and D/42-xx, as well as emulating phones connected to a PBX. With the current D/42-xx PBX Integration boards, it is necessary to choose a particular board depending on which PBX you plan to use. With the PBX Integration board, however, a single board can work with several different PBXs, with the software configuration selected to reflect the PBX in use.

When recording speech, the PBX Integration board digitizes it as Pulse Code Modulation (PCM), Adaptive Differential Pulse Code Modulation (ADPCM), GSM 610, or G.726. The digitizing rate is selected on a channel-by-channel basis and can be changed each time a record or play function is initiated. The processed speech is stored on the host PC's hard disk. When playing back a stored file, the voice information from the host PC is passed to the PBX Integration board where it is converted into analog voice signals for transmission to the PBX.

The on-board control processor controls all operations of the PBX Integration board via a local bus and interprets and executes commands from the host PC. This processor handles real-time events, manages data flow to the host PC to provide faster system response time, reduces PC host processing demands, processes DTMF and PBX signaling before passing them to the application, and frees the DSP to perform signal processing. Communication between this processor and the host PC is via the shared buffer memory that acts as an input/output buffer and thus increases the efficiency of disk file transfers. This shared buffer memory interfaces to the host PC via the PCI bus.

Click here to contact Dialogic Customer Engineering