Dear Treggers, Can anyone answer the following questions relating to message-waiting indications on CO lines?
1. A message-waiting indication facility is commonly available for PBXs, and is intended for the hotel/motel market. The systems that I have encountered use a neon lamp mounted in each guest's telephone set, which is illuminated by a higher than normal telephone line voltage -- 150 volts or so -- when the guest has messages waiting. Assuming that a voice mail service is provided by US telephone companies (is this assumption correct?) on CO lines, is a message-waiting lamp feature available, and if so, does it use the high DC voltage arrangement of the kind described above? 2. I have seen a reference to a Visual Message Waiting display being available from US West to customers whose lines support CLASS/Call Management Services or "voltage message waiting indication" (and who subscribe to Voice Mail service). The name "voltage message waiting indication" seems to refer to an arrangement of the kind used in hotels. However, the reference to CLASS hints at the use of caller ID data fields to indicate that voice mail messages have been stored. It appears that a message-waiting indication may be delivered to subscribers using either of these methods, both of which may be supported on the same line. Can anyone confirm these inferences on my part? 3. If, indeed, caller ID is used to indicate that messages are waiting, which Standard specifies the protocol used for transmitting this specific information? 4. If a high voltage is used on CO lines for message-waiting indication, which voltage is used? Am I right in assuming that during incoming ringing, the superimposed DC voltage temporarily reverts to the normal 42-56 volt range, to prevent the combined total peak line voltage (DC + peak AC) from exceeding the acceptable limit for subscribers' equipment that has been designed to meet FCC Part 68? Thanks in advance for any information received, David Drori ----------------------------------------------------------- Novarex Enterprises Ltd., POB 2833, 306-6, Mevo Hapartisanim Street, Jerusalem 91028, Israel. Tel: +972 2 5810 995 Fax: +972 2 5813 750 E-mail: [email protected] -----------------------------------------------------------
