Randolph Telecom

Telecom Project Profiles

Phone Line Interface Circuit Design
Designed a family of high density line cards that implemented full featured loop start and ground start FXS and FXO ports for a voice/fax server. Assisted the client with obtaining international regulatory approvals in multiple countries.

International Regulatory Approvals
Client had an existing North American VOIP product that they wished to begin selling internationally. Randolph Telecom conducted a design review and performed selected laboratory tests to identify all areas of non-compliance with the regulatory requirements of the target countries. Randolph Telecom then recommended specific design changes to correct all known deficiencies, supervised the implementation of the changes, and assisted the client with obtaining approval in all target countries.

Telcordia GR-1089-CORE Compliance
Client had designed a family of IP telephony products for use in the public network, but the products failed both the lightning and power cross tests in Telcordia GR-1089. A large sale to a major North American carrier was put on hold until the problems could be resolved. Randolph Telecom reviewed and then redesigned a total of six different line cards that implemented functions such as FXS, FXO, T1 and DSL services. All six modified line card designs passed GR-1089 on the first attempt, and the sale to the major carrier was completed.

Modem Circuit Design
Designed a high speed modem for use in international markets, where client wanted to use a single, configurable design in approximately 100 different countries. Randolph Telecom designed the line interface and assisted with obtaining approvals in all target countries.

Expert Witness
Mr. Randolph has served as an expert witness in various patent cases related to telecom product designs. He has a good working knowledge of patent litigation and has considerable experience with analyzing prior art and with explaining complex technology in a courtroom setting.

Troubleshooting Lightning Failures
Mr. Randolph has extensive experience troubleshooting and fixing problems with lightning protection. He has successfully resolved lightning problems in dozens of products, including fax machines, set top boxes, alarm dialers, line cards, data modems, DSL modems, loop carrier systems, and broadband fiber systems. Some of these products were being sold in very high volumes and the savings from reduced failure rates were several million dollars per year.

VOIP PBX Design
Designed the analog PSTN interfaces for an IP telephony PBX product. These included FXO ports supporting both loop start and ground start, FXS ports supporting both local extensions and DID services, and a high speed modem for dial backup services. Special attention was given to managing echo in the analog portions of the interfaces and coordinating the analog functions with the DSP echo cancellers to achieve a high quality of service for connections to the PSTN.

Cost Reduction Design Review
Performed a comprehensive design review of a complex network product that was performing properly but was not achieving the client's manufacturing cost target. Interviewed key members of the client's design team and developed a redesign strategy that incorporated changes in the hardware, software, and physical design of the product. Client implemented the recommendations and achieved a 60% reduction in manufacturing cost. Sales of the redesigned product exceeded $50 million.

Troubleshooting 50/60 Hz Hum in an IP Telephone
Client had developed an IP telephone that had a problem with 50/60 Hz hum in the audio path, but only in certain installations and under certain operating conditions. Client had been unsuccessful in resolving the problem for over two years, and customer dissatisfaction was becoming a critical issue. Randolph Telecom analyzed the available field data, developed a laboratory procedure for simulating the problem, found the cause of the problem and fixed it.

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