Telecom@usc-eclb@brl-bmd.UUCP (08/03/83)
TELECOM Digest Wednesday, 3 Aug 1983 Volume 3 : Issue 46 Today's Topics: Access Charges Another Bad Telephone Number To have. On Modems Which Replace Handsets ---------------------------------------------------------------------- Date: 2 August 1983 09:27 EDT From: "Marvin A. Sirbu, Jr." <SIRBU @ MIT-MC> Subject: access charges If there was a special rate for people who didn't make long distance calls, it would be just as much as local rates with access charges. While the bill may say that "access" charges are for access to the long distance network, what they really pay for is the wire between your house and the nearest central office, plus the fixed cost parts of the office switch. You need all that equipment just to make local calls, so saying you aren't going to make any long distance calls doesn't reduce the COSTS of "access" one dime. There is local equipment which is used only by people making long distance calls -- for example, the trunk from the local office to the "point of presence" of the interexchange carrier. The cost of this equipment WILL be billed directly to the interexchange carriers. As to billing "access" charges to long distance carriers, why should someone who makes more minutes of long distance calls pay more for some fixed plant whose cost doesn't vary with usage? And if you do try and tack the cost of local access onto the long distance bill, how do you keep the big users of long distance from putting up their own satellite or microwave system to escape the charges? The only way to keep the subsidy from long distance to local service is to go back to the 1950s and get rid of all the competition in the telephone business. Countries like Japan or France succeed in maintaining the cross subsidy by simply forbidding competitive carrier, satellites and private microwave systems. Marvin Sirbu ------------------------------ Date: Tue 2 Aug 83 10:17:12-CDT From: Rick Watson <CC.RICK@UTEXAS-20.ARPA> Subject: Another bad telephone number to have. I had 512/454-1212 for about a year (note similarity to 555-1212). We sometimes got so tired of explaining to the person that he didn't really have directory assistance that we would often just look up the number in the phone book. It was also fun to chat with the callers about the weather in Seattle, etc... ------------------------------ Date: Tue, 2 Aug 83 17:16:06 PDT From: Theodore N. Vail <vail@UCLA-ATS> Subject: On Modems Which Replace Handsets On Modems Which Replace Handsets Modems, such as the Atari and the Hayes, which are made to connect in place of the handset on a telephone, are intended for use with the full-modular version of the Western Electric (or equivalent) model 500 and 2500 telephones. The 500 is the standard dial telephone introduced in the 1950's; the 2500 is the corresponding touch-tone telephone. These phones use what is usually called a "network"; this contains most of the electronic components of the phone (excluding a couple of diodes which sit on the receiver, limiting the voltage going to the receiver, and a capacitor in series with the ringer). Used networks are available for around $1.00. They are taken from phones removed from service and are available from telephone surplus houses such as Telectric Company, 1218 Venice Boulevard, Los Angeles. They are extremely reliable: I have never seen a used network which did not work. Essentially identical networks can be found in the corresponding telephones made by Stromberg-Carlson, Northern Electric, ITT, and others, but excluding General Tinkle (G. T and E.) which seems to like to be different from the others. More recent telephones, with electronic touch-tone circuits do not use these networks. The networks are potted in rectangular cans, about 2.5 by 2.5 by 1.5 inches, with one face covered with screw terminals. They serve, among other things, the following purposes: 1. They compensate for the distance of the telephone to its central office (the resistance of the subscriber line loop) or for the fact that more than one telephone may be in use on the circuit. 2. They have a multi-winding transformer which (a) increases the output from the transmitter (carbon microphone), (b) increases the voltage to the receiver, while at the same time not allowing dc voltage to go to the receiver, and (c) controls the amount of signal which goes from the transmitter to the receiver (sidetone). 3. Provide an impedance match at audio frequencies to the subscriber line loop. 4. In the case of dial phones, they contain a filter which decrease the sparking from the opening and closing of the dial contacts. 5. In the case of touch-tone phones, they (together with a switch) decrease the volume of the tones heard by the user when the touch-tone buttons are pressed. The screw-terminals on these networks are labeled with one or two letters or numerals. The lettering is either adjacent to the screw-terminals or on the side of the modem. To use these networks, independent of a telephone set, the telephone line should be connected to the terminals marked C and RR (not L1 and L2!). The receiver (or its modem equivalent) should be connected to R and GN and the transmitter (or its modem equivalent) should be connected to R and B. Note that the polarity of the line is irrelevant. Indeed on older exchanges the polarity sometimes reverses when dialing nearby old exchanges; the reason for this is another story. However, this is the reason that touch-tone phones sometimes don't work when calling Sprint or MCI. The Telephone Company provides a "polarity guard" (in reality, a full-wave bridge) to solve the problem. If there are three wires going to your telephone, it is normally the red and green which are used; the third, if connected, is a ground. To disconnect the network from the circuit, it suffices to have a single- pole, single-throw switch disconnecting the wire going to C or the wire going to RR. To use the device, connect it in parallel with your telephone and connect your modem as indicated above (you will have to obtain the appropriate female modular jacks -- note these are not the RJ11 jacks which telephones plug into). Turn it off with its switch and dial your favorite computer on your phone. When you get the answer tone, switch the device on, hang up your telephone, and communicate. ------------------------------ End of TELECOM Digest *********************