14. What is a loop?

This FAQ answer is excerpted from:
ToneLoc v0.99 User Manual by Minor Threat & Mucho Maas
Loops are a pair of phone numbers, usually consecutive, like 836-9998 and
836-9999. They are used by the phone company for testing. What good do
loops do us? Well, they are cool in a few ways. Here is a simple use of
loops. Each loop has two ends, a 'high' end, and a 'low' end. One end gives
a (usually) constant, loud tone when it is called. The other end is silent.
Loops don't usually ring either. When BOTH ends are called, the people that
called each end can talk through the loop. Some loops are voice filtered
and won't pass anything but a constant tone; these aren't much use to you.
Here's what you can use working loops for: billing phone calls! First, call
the end that gives the loud tone. Then if the operator or someone calls the
other end, the tone will go quiet. Act like the phone just rang and you
answered it ... say "Hello", "Allo", "Chow", "Yo", or what the fuck ever.
The operator thinks that she just called you, and that's it! Now the phone
bill will go to the loop, and your local RBOC will get the bill! Use this
technique in moderation, or the loop may go down. Loops are probably most
useful when you want to talk to someone to whom you don't want to give your
phone number.

15. What is a loop in my area?

Many of these loops are no longer functional. If you are local to any of
these loops, please try them out an e-mail me the results of your research.

  NPA    High      Low
  ---  --------  --------
  201  879-9929  879-9930
  201  347-9929  347-9930
  206  827-0018  827-0019
  206  988-0020  988-0022
  208  862-9996  862-9997
  209  732-0044  732-0045
  201  666-9929  666-9930
N 210  993-9929  993-9930
N 210  330-9929  330-9930
N 210  333-9929  333-9930
N 210  376-9929  376-9930
N 210  467-9929  467-9930
  212  220-9977  220-9979
  212  283-9977  283-9979
  212  283-9977  283-9997
  212  352-9900  352-9906
  212  365-9977  365-9979
  212  529-9900  529-9906
  212  562-9977  562-9979
  212  986-9977  986-9979
  213  360-1118  360-1119
  213  365-1118  365-1119
  213  455-0002  455-XXXX
  213  455-0002  455-xxxx
  213  546-0002  546-XXXX
  213  546-0002  546-xxxx
  213  549-1118  549-1119
  214  291-4759  291-4757
  214  299-4759  299-4757
  305  778-9952  778-9951
  305  964-9951  964-9952
  307  468-9999  468-9998
  308  357-0004  357-0005
N 310  365-1118  365-1119
N 310  445-0002  445-????
N 310  455-0002  455-????
N 310  545-0002  545-????
N 310  546-0002  546-????
N 312  262-9902  262-9903
  313  224-9996  224-9997
  313  225-9996  225-9997
  313  234-9996  234-9997
  313  237-9996  237-9997
  313  256-9996  256-9997
  313  272-9996  272-9997
  313  273-9996  273-9997
  313  277-9996  277-9997
  313  281-9996  281-9997
  313  292-9996  292-9997
  313  299-9996  299-9997
  313  321-9996  321-9997
  313  326-9996  326-9997
  313  356-9996  356-9997
  313  362-9996  362-9997
  313  369-9996  369-9997
  313  388-9996  388-9997
  313  397-9996  397-9997
  313  399-9996  399-9997
  313  445-9996  445-9997
  313  465-9996  465-9997
  313  471-9996  471-9997
  313  474-9996  474-9997
  313  477-9996  477-9997
  313  478-9996  478-9997
  313  483-9996  483-9997
  313  497-9996  497-9997
  313  526-9996  526-9997
  313  552-9996  552-9997
  313  556-9996  556-9997
  313  561-9996  561-9997
  313  569-9996  569-9996
  313  575-9996  575-9997
  313  577-9996  577-9997
  313  585-9996  585-9997
  313  591-9996  591-9997
  313  621-9996  621-9997
  313  626-9996  626-9997
  313  644-9996  644-9997
  313  646-9996  646-9997
  313  647-9996  647-9997
  313  649-9996  649-9997
  313  663-9996  663-9997
  313  665-9996  665-9997
  313  683-9996  683-9997
  313  721-9996  721-9997
  313  722-9996  722-9997
  313  728-9996  728-9997
  313  731-9996  731-9997
  313  751-9996  751-9997
  313  776-9996  776-9997
  313  781-9996  781-9997
  313  787-9996  787-9997
  313  822-9996  822-9997
  313  833-9996  833-9997
  313  851-9996  851-9997
  313  871-9996  871-9997
  313  875-9996  875-9997
  313  886-9996  886-9997
  313  888-9996  888-9997
  313  898-9996  898-9997
  313  934-9996  934-9997
  313  942-9996  942-9997
  313  963-9996  963-9997
  313  977-9996  977-9997
  315  673-9995  673-9996
  315  695-9995  695-9996
  402  422-0001  422-0002
  402  422-0003  422-0004
  402  422-0005  422-0006
  402  422-0007  422-0008
  402  572-0003  572-0004
  402  779-0004  779-0007
  406  225-9902  225-9903
  517  422-9996  422-9997
  517  423-9996  423-9997
  517  455-9996  455-9997
  517  563-9996  563-9997
  517  663-9996  663-9997
  517  851-9996  851-9997
  609  921-9929  921-9930
  609  994-9929  994-9930
  616  997-9996  997-9997
N 708  724-9951  724-????
  713  224-1499  759-1799
  713  324-1499  324-1799
  713  342-1499  342-1799
  713  351-1499  351-1799
  713  354-1499  354-1799
  713  356-1499  356-1799
  713  442-1499  442-1799
  713  447-1499  447-1799
  713  455-1499  455-1799
  713  458-1499  458-1799
  713  462-1499  462-1799
  713  466-1499  466-1799
  713  468-1499  468-1799
  713  469-1499  469-1799
  713  471-1499  471-1799
  713  481-1499  481-1799
  713  482-1499  482-1799
  713  484-1499  484-1799
  713  487-1499  487-1799
  713  489-1499  489-1799
  713  492-1499  492-1799
  713  493-1499  493-1799
  713  524-1499  524-1799
  713  526-1499  526-1799
  713  555-1499  555-1799
  713  661-1499  661-1799
  713  664-1499  664-1799
  713  665-1499  665-1799
  713  666-1499  666-1799
  713  667-1499  667-1799
  713  682-1499  976-1799
  713  771-1499  771-1799
  713  780-1499  780-1799
  713  781-1499  997-1799
  713  960-1499  960-1799
  713  977-1499  977-1799
  713  988-1499  988-1799
  805  528-0044  528-0045
  805  544-0044  544-0045
  805  773-0044  773-0045
  808  235-9907  235-9908
  808  239-9907  239-9908
  808  245-9907  245-9908
  808  247-9907  247-9908
  808  261-9907  261-9908
  808  322-9907  322-9908
  808  328-9907  328-9908
  808  329-9907  329-9908
  808  332-9907  332-9908
  808  335-9907  335-9908
  808  572-9907  572-9908
  808  623-9907  623-9908
  808  624-9907  624-9908
  808  668-9907  668-9908
  808  742-9907  742-9908
  808  879-9907  879-9908
  808  882-9907  882-9908
  808  885-9907  885-9908
  808  959-9907  959-9908
  808  961-9907  961-9908
  810  362-9996  362-9997
  813  385-9971  385-xxxx
N 908  254-9929  254-9930
N 908  558-9929  558-9930
N 908  560-9929  560-9930
  908  776-9930  776-9930
