Dear Treggers, Can anyone answer the following questions:
1. What are the specific North American and European safety requirements (isolation, power-cross) relating to a telephone exchange supporting on-premise extensions (usual DC and ringing voltages), powered from a 2-pin 12 VDC mains adaptor (and therefore unearthed), and equipped with a 10BASE-T port? The supply voltages are generated using a switching regulator mounted within the product, supplying the logic (5 volts) and the telephone extension feeds (current-limited 24-volt off-hook and 60-volt for current-limited trapezoidal-waveform ringing). We intend to design the circuitry with a common return line for the 5-volt, 24-volt and 60-volt lines, which means that there will be no isolation between them. Furthermore, we do not intend to provide isolation between these voltages and the unregulated 12-volt input. Isolation will be provided by the external mains adaptor. 2. Are there any North American or European mandatory telephony requirements relating to the connection of the above exchange to standard subscribers' line equipment (telephone sets, modems, fax machines, etc.), or is this purely a market-driven product quality factor (with voluntary requirements such as EIA and BELLCORE requirements)? 3. Are the answers to the above influenced by the range (distance from the exchange to the subbscriber's line equipment) of the extensions and whether they are permitted to pass from one building to another within the customer's premises? 4. If voice signals derived from the telephone exchange and its extensions are delivered to the public network (analog PSTN or E1/T1 digital trunks) by means of off-the-shelf PC-based line interface boards with FCC Part 68 and European approval (such as Dialogic boards), does the above picture change? 5. If a certain item of subscriber's line equipment is intended solely for connection to a PBX extension, and never to the public telephone network, is the equipment subject to exemption from North American and European telephony requirements and regulatory procedures, and to the power-cross requirement, and therefore subject to sale purely on the basis of UL (except power-cross) and FCC Part 15 compliance (North America), or CE mark (European safety and EMC requirements only)? Best regards, David Drori Novarex Enterprises Ltd., POB 2833, Jerusalem 91028, Israel. Tel: +972 2 581 0995 Fax: +972 2 581 3750 Mobile: +972 50 678686 E-mail: [email protected]
