Vendor Network Architectures�Part LVIII: Epygi

Epygi Technologies, Ltd. Is a privately held company based in Plano, Texas. Founded in 2000, Epygi designs and manufactures all-in-one IP PBXs, VoIP gateways, and cost-saving conference servers. The Epygi products are positioned to serve the small and medium business (SMB) and small office/home office (SOHO) markets, plus teleworkers and branch offices of large corporations. The firm has over 125 employees worldwide, with product solutions that address the customers of global telecom companies, Internet service providers, and cable operators. Epygi has established a strong global presence working through distributors and resellers around the world, with its products presently in operation in over 40 countries on 6 continents.

Epygi’s line of IP-based PBXs is called Quadro, and is designed to offer communication features and services to SMBs that are typically only available in much larger systems. Quadros are distinguished by being extremely easy to install, configure, and maintain. In addition, they are amazingly compact—about the size of a large book. For the ever-growing mobile employee and teleworker populations, advanced Quadro features such as call forwarding, voicemails as e-mails, and the ability to call from a laptop allow businesses to overcome traditional geographic and telecom device constraints.

The architecture of the Quadro is based upon a core system called the Call Manager, which resides on a CPU running Linux. The Call Manager determines the status of both incoming (line) and outgoing (station) ports and then establishes and terminates calls. The same module also performs the traditional PBX operations, such as call hold, call transfer, and voicemail functions, and sends voice streams to a digital signal processor for voice compression. After compression, Internet Protocol (IP) headers are added to the voice samples, which are then routed to the Internet for packet delivery.

There are two different versions of the Quadro products: one set that supports traditional telephone lines (the models 2x, 4x, 4xa and 16x), and one set that supports ISDN lines (the models 2xi, 4xi, and 16xi). System capacities are designed to match a wide range of SMB requirements, with concurrent calls to the PSTN and Internet or IP networks allowed.

Maximum capacities are:

2x models 1 phone line, 2 phone extensions
4x models 4 lines, 4 extensions, 16 LAN IP phones
16x models 4 lines, 16 extensions, 48 LAN IP phones

All systems have a maximum capacity of one Ethernet LAN port and one Ethernet WAN port, with the model 4xa having the additional capability of an ADSL WAN interface.

Consistent across all of the models is a wide range of PBX features, including call hold, blocking, forwarding, ID, relay and transfer; voice mail, auto attendant, directory assistance, blind transfer, and consultative transfer; conferencing, many extension ringing, and call routing by caller ID; unified messaging; dialing plans including time of day dialing, plus support for T.38-compliant fax machines. In addition, all models support an array of voice coding algorithms, including G.711, G.723, G.726 and G.729, plus both analog loop start and Session Initiation Protocol (SIP) signaling.

The Quadro has an interesting remote access feature that should appeal to remote users and teleworkers. When you call from outside the office, the Caller ID algorithm in the Quadro recognizes your mobile phone number and authenticates your access to the system. You can then dial an extension number, which the system will place via the most optimum route. In a similar fashion, office workers that will be traveling can leave call forwarding and call routing instructions with the system, so that they can be reached automatically.

Additional Quadro features that are not typically included in systems of this size include power fail transfer—which automatically connects to the Public Switched Telephone Network (PSTN) in the event of a power failure—a firewall and virtual private network (VPN) for greater security of both the voice and data communication, and a traffic shaping algorithm that gives priority to voice traffic over data traffic, in order to optimize voice quality.

Further details on the Epygi products and architectures can be found at Our next tutorial will continue our examination of vendors’ architectures.

Copyright Acknowledgement: © 2007 DigiNet ® Corporation, All Rights Reserved

Author’s Biography
Mark A. Miller, P.E. is President of DigiNet ® Corporation, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including Voice over IP Technologies, and Internet Technologies Handbook, both published by John Wiley & Sons.

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