aka POTS (Plain Old Telephone Service)
Phone Number Directories
Location Data From Phone Number
http://www.AreaDecoder.com Country and Area Codes. Forward and reverse. Partial matches ok. Nice job. See also
Phone line interfaceing
Voice Mail Systems
D.C. Line Voltage (Talk Battery) - 48v with receiver on-hook, red wire (ring) negative, 5v for off-hook (with 50-1000 ohm d.c. load on line).
Tip and ring get their name from the construction of an operator's plug-board plug -- tip was the tip, and ring was the ring below the tip. The positive voltage (ground) was put on the tip line, because that was the part of the plug that the operator had the least chance of touching. Negative battery supplies (with respect to ground) have always been used with phone systems, so that leakage currents to ground caused by moisture do not electroplate away the copper in the wires.
Call Progress Tones in the US (from many sources includeing Telecom Digest, Dan Michaels and others as listed)
From the documentation that I have, there are four different sequencesof tones:First Tone Second Tone Third Tone Tone Tone freq length freq length freq length Name Description (Hz) (10 ms) (Hz) (10 ms) (Hz) (10 ms) ====================================================================== NC No Circuit 985.2 38.0 1428.5 38.0 1776.7 38.0 Found IC Operator 913.8 27.4 1370.6 27.4 1776.7 38.0 Intercept VC Vacant Circuit 985.2 38.0 1370.6 27.4 1776.7 38.0 RO ReOrder 913.8 27.4 1428.5 38.0 1776.7 38.0
Macy Hallock of F M Systems, Inc. 150 Highland Dr. Medina, OH 44256 says:
Period Frequency Designation SSL LLL IC - Intercept - Vacant No. or AIS or etc. LLL LLL NC - No Circuit (Inter-LATA carrier) LSL HLL VC - Vacant Code SLL HLL RO - Reorder Announcement (Inter-LATA Carrier) LSS LHL #1 - Add'l Reserved Code SLL LHL RO - Reorder Announcement SSL HHL #2 - Add'l Reserved Code LLL LLL NC - No Circuit, Emergency or Trunk Blockage Where: Period-Duration: S=Short 274 msec L=Long 380 msec Frequency: L=Low 913.8 hz 1370.6 hz 1776.7 hz H=High 985.2 hz 1428.5 hz
This information taken from a central office recorder/announcer installation manual ca. 1983. I believe SIT's are specified by Bellcore and/orr CCITT. I have heard SIT's used on international calls to several countries.
Teltone (http://www.teltone.com) makes a detector chip; part number
The GSM specification (mostly) requires phone numbers in the format
+XXX-LLL-YYYYYYYYY... + = International access XXX = country code LLL = local area code yyy = number
This string cannot exceed 12 digits
Speech@ Fax@ Pagers@ Modems@ DTMF@ Cellular@
http://embedworx.com/articles/index.html The phoneswitch.com url is outdated. The correct URL is here: http://embedworx.com/articles/index.html I'm the author of the original Personal PBX article. Thank you.
James Newton replies: Thanks for the update!+
I am looking for a gadget similar to what my friend, Vinny, has. I call it their 'Do Not Disturb gadget'. They bought it at least 10 years ago and I have never seen its like. It sits there on the telephone line, like an answering machine. But when you call his number it answers, usually on the first or second ring. It does not say anything (but I am OK if the one I buy says a message), but unless you enter the special three-digit code (I am cool with more or less digits) your call is going nowhere. When you enter the code, then it 'passes' the call, -- that is, other telephone(s) on the line ring -- and if they are at home one of them will answer. There is no audible ring anywhere in the house until then.
James Newton reffers to : "http://www.hometownvariety.com/wholesalestuff/digcalfil.html".
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