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Automatic Testing of Voice Networks Cuts Costs While Increasing Quality.

Voice-circuit testing methods for thousands of private telecommunications systems, now superimposed on a fragmented public-switched network, are in the midst of radical change born out of necessity. Faced with maintenance responsibilities for their own systems, many private-system telecom managers opt for more technicians packing a variety of manual test sets. Or they consider expensive and inflexible matrix or switched testing systems hardwired to all critical circuits. Budget constraints have even forced some back to crude operator ear testing and reporting to a central control.

All those methods have been rendered obsolete for voice networks by automatic test systems that install as easily as a telephone, have superior capabilities, and sharply improve network quality while cutting costs.

The development of automatic circuit-testing systems could hardly be more timely. While private-network telecom managers have been busy since deregulation building in data capabilities and reducing system costs per minute with new transmission equipment and facilities, they now find that voice-circuit quality has declined.

In the new multi-vendor environment, end-to-end testing of the public-switched network and of its interfaces with the thousands of new private systems has become imperative.

Private-system managers find that fixing responsibility for a circuit or trunk problem among several vendors is a frustrating experience. They have also optimized their systems to such a degree that redundant circuitry is virtually non-existent. Therefore, the spillover onto more-expensive off-net facilities can be expensive if circuits are in poor condition. Also, the impact of ISDNs and SDNs must be considered.

As a result, many private telecom managers are now studying various testing methods to maximize usage of existing circuitry. Having purchased state-of-the-art PBXs, sophisticated billing systems and network-optimization software, they view automatic testing as low-cost quality insurance. Also, this new technology offers full payback in a matter of months, frees operators and technicians from testing involvement and, especially important, eliminates vendor hassling.

60 Private-System Test Results

A combined analysis of the initial test results in 60 private systems serviced by our Janus automatic dial-line analyzer indicated widespread private-system circuit problems.

These systems represent a cross-section of American industry. Their combined defective-circuit rate initially ranged from 10 to 27 percent. Subsequently, automatic testing reduced the rate to 2 to 5 percent in every instance, and kept it there.

In a 1,000-circuit network, which a single automatic console is capable of testing, the number of defective circuits can be reduced from 100 to 50 or less. Assuming an average 10 percent defect rate and a cost of $1,500 per circuit for a typical large network, a minimum of $75,000 would be saved by eliminating the need for 50 new circuits to achieve the same level of efficiency. That's several times the cost of such a testing system.

Also eliminated are the costs of testing man-hours for a technician, and the cost of overflows onto non-network facilities is reduced. A study showed that 150 hours of coast-to-coast WATS calls will cost $511 more than the equivalent hours of calls made on some OCCs that provide discount long-distance services. And if 150 hours of calls are forced over central-office trunks, they would cost $2,907 more.

The latest software-controlled, peripheral automatic-testing systems have three related components: Desktop or rack-mounted control consoles, which access the PBX in various ways; tone responders, which are accessed through dedicated tie lines or public-switched circuits; and optional trunk identification units (TIDs), which extend testing capabilities to include INWATS and direct inward dial (DID) lines.

Consoles vary in capability, depending on whether they are for single-location users or for large multi-nodal networks. SMaller consoles test up to 200 circuits with a tone responder.

In addition to testing for two-way level and noise, echo-return measurements and singing-return loss like their smaller cousins, the larger systems should also be expected to report peak-to-average ratio, which will determine the suitability of voice lines for data transmission.

The trunk identification unit is a peripheral component that's particularly valuable when merchant or service ordering by phone is critical, and must be prompt because of a competitive situation. The TIDs help because they allow testing of DID and INWWATs trunks that are not directly accessible from a PBX or switch. ACD users are also interested in the TIDs because the testing of inbound circuits is critical to their business.

Printout Option Is Available

Generally, it takes a day's training for users to understand what they are reading and to operate the system. For simplicity, the option of printouts on out-of-spec or down circuits is often preferred. The advantage of a full report, however, is that preventive reporting to the proper vendor may be accomplished before a circuit actually breaks the test boundaries. While this takes more staff reading time, it keeps circuit conditions at the highest-possible level of their operating efficiency.

At prices ranging as low as $12,000 for single-location telecommunications systems, automatic network testing is the most-economical solution to circuit problems. It pinpoints deficiencies before the complaints roll in, or worse, before the automatic routing system deflects too many calls outside the network, which are not discovered until telco bills arrive.

Automatic testing allows the telecom manager and his vendors to agree on acceptable standards of performance and provides written documentation that avoids hassling between them. If all the expensive components of the network function properly, it reduces dependence on telcos and OCCs for diagnostics and frees internal staff from testing chores. After a short payback period, automatic testing begins to make a real dent in total facilities costs.
COPYRIGHT 1986 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1986 Gale, Cengage Learning. All rights reserved.

Article Details
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Author:Brown, Samuel
Publication:Communications News
Date:Feb 1, 1986
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