Telecom Project Profiles

Troubleshooting Lightning Failures

A networking product was experiencing a high field-failure rate due to lightning surges on a variety of cable ports including power, outside cables, and inside Ethernet cables. Client had attempted to add more surge protection to the circuit design, but the field failure rate remained high. Based on a forensic analysis of damaged circuit boards and an analysis of the system interconnects, Randolph Telecom diagnosed the root cause of the failures and proposed a set of cost effective circuit design changes that reduced the field failure rate by over 90%.

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 for various port types. All six of the modified line card designs passed GR-1089 on the first attempt, and the sale to the major carrier was completed.


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.

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.

Expert Witness

Mr. Randolph has served as an expert witness in several 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.