THE QUESTION
THE ANSWER

The PPL was originally developed to address variations found in E1 signaling protocols worldwide. Because of its flexibility, it has become Excel's standard used in the development of all new and enhanced network signaling components. PPL is designed to reside in each major line and service card supported by Excel switching platforms. PPL consists of two parts: the PPL Environment, residing in the base system software; and, the PPL Tool, the software that developers use to generate custom switch-based software.

The PPL Tool allows developers to quickly modify software using a graphical state machine flow chart.

PPL Environment

The PPL environment software is designed into the LNX or PCX system software and resides on those components of the switch that are PPL controlled. The PPL environment integrates custom PPL-generated software with the generic software residing on the card. It supports the creation and downloading of multiple call processing control state machines. The developer has the power to determine which call processing events will be processed by the switch and how the switch will react to these events. Multiple different control state machines can be defined for each PPL-managed switch component and selectively assigned to the objects being managed on a per channel basis (i.e., voice channels, ISDN Data Link connections, etc.).

The PPL is extremely flexible. It can be used to develop custom E1 R2 signaling protocols, whether in the lab or in the field, eliminating vendor intervention and unnecessary delays. PPL can be used to play out voice prompts and collect or filter digits on an incoming call, achieving improved performance while reducing host interaction. PPL can be used to build and manage call processing sequences, again reducing host communications overhead and improving system performance. It can be used to create a series of interactive voice responses, reducing external voice resource requirements and resulting in cost savings. And it can be used with common channel signaling services such as SS7 and ISDN to provide more powerful call processing control in the switch.

PPL Tool

Using a simple-to-use graphical user interface (GUI), developers have access to software at a level not available on other platforms. The developer uses the PPL Tool on a Windows-based PC, where state machines can be created or modified by editing the Excel standard templates using "point and click" technology. The PPL Tool automatically converts a graphical state machine flow chart into a state table configuration which can then be downloaded and activated in the switch. Excel has developed a library of E1 signaling protocols, available to customers .

PPL-based software is created independently of the switch software, supporting the creation of new services without requiring a system software upgrade. The software is created using high-level atomic functions, insulating the developer from the detailed implementation logic. Multiple control state machines can be defined for each PPL-managed switch component and selectively assigned to the objects being managed on a per channel basis. The PPL also supports dynamic switching between different protocols.

Programmable E1 R2 Signaling

Due to variations in E1 line signaling worldwide, the PPL was developed to address the need for adaptability in a simple to use, programmable state machine environment. Together, the PPL Environment and PPL Tool provide the ability to create and download up to 10 custom protocols on a per-channel basis to the LNX, CSN or PCX, giving the developer full control over call processing. Network line signaling such as DTMF, MFR1, and MFR2, is defined and controlled by the PPL protocol.

Programmable Common Channel Signaling

Excel's SS7 and ISDN Common Channel Signaling packet engines are also designed to support PPL programmability. With PPL, developers can customize the processing of common channel signaling information, using the same tools available