|  | H |
SECTION H — ELECTRICITY

|  | H |
Note(s) These Notes cover the basic principles and general instructions for use of section H. Section H covers: basic electric elements, which cover all electric units and the general mechanical structure of apparatus and circuits, including the assembly of various basic elements into what are called printed circuits and also cover to a certain extent the manufacture of these elements (when not covered elsewhere); generation of electricity, which covers the generation, conversion and distribution of electricity together with the controlling of the corresponding gear; applied electricity, which covers: general utilisation techniques, viz. those of electric heating and electric lighting circuits; some special utilisation techniques, either electric or electronic in the strict sense, which are not covered by other sections of the Classification, including: electric light sources, including lasers; electric X-ray technique; electric plasma technique and the generation and acceleration of electrically charged particles or neutrons; basic electronic circuits and their control; radio or electric communication technique; the use of a specified material for the manufacture of the article or element described. In this connection, paragraphs 88 to 90 of the Guide should be referred to. In this section, the following general rules apply: Subject to the exceptions stated in I(c), above, any electric aspect or part peculiar to a particular operation, process, apparatus, object or article, classified in one of the sections of the Classification other than section H, is always classified in the subclass for that operation, process, apparatus, object or article. Where common characteristics concerning technical subjects of similar nature have been brought out at class level, the electric aspect or part is classified, in conjunction with the operation, process, apparatus, object or article, in a subclass which covers entirely the general electrical applications for the technical subject in question; The electrical applications referred to under (a), above, either general or particular, include: the therapeutic processes and apparatus, in class Fulltext... Hierarchy... Expanded...A61; the electric processes and apparatus used in various laboratory or industrial operations, in classes Fulltext... Hierarchy... Expanded...B01 and Fulltext... Hierarchy... Expanded...B03 and in subclass Fulltext... Hierarchy... Expanded...B23K; the electricity supply, electric propulsion and electric lighting of vehicles in general and of particular vehicles, in the subsection "Transporting" of section B; the electric ignition systems of internal-combustion engines, in subclass Fulltext... Hierarchy... Expanded...F02P, and of combustion apparatus in general, in subclass Fulltext... Hierarchy... Expanded...F23Q; the whole electrical part of section G, i.e. measuring devices including apparatus for measuring electric variables, checking, signalling and calculating. Electricity in that section is generally dealt with as a means and not as an end in itself; All electrical applications, both general and particular, presuppose that the "basic electricity" aspect appears in section H (see I(a) above) as regards the electric "basic elements" which they comprise. This rule is also valid for applied electricity, referred to in I(c), above, which appears in section H itself. In this section, the following special cases occur: Among the general applications covered by sections other than section H, it is worth noting that electric heating in general is covered by subclasses Fulltext... Hierarchy... Expanded...F24D or Fulltext... Hierarchy... Expanded...F24H or class Fulltext... Hierarchy... Expanded...F27, and that electric lighting in general is partly covered by class Fulltext... Hierarchy... Expanded...F21, since in section H (see I(c), above) there are places in Fulltext... Hierarchy... Expanded...H05B which cover the same technical subjects; In the two cases referred to under (a), above, the subclasses of section F, which deal with the respective subjects, essentially cover in the first place the whole mechanical aspect of the apparatus or devices, whereas the electrical aspect, as such, is covered by subclass Fulltext... Hierarchy... Expanded...H05B; In the case of lighting, this mechanical aspect should be taken to cover the material arrangement of the various electric elements, i.e., their geometrical or physical position in relation to one another; this aspect is covered by subclass Fulltext... Hierarchy... Expanded...F21V, the elements themselves and the primary circuits remaining in section H. The same applies to electric light sources, when combined with light sources of a different kind. These are covered by subclass Fulltext... Hierarchy... Expanded...H05B, whereas the physical arrangement which their combination constitutes is covered by the various subclasses of class Fulltext... Hierarchy... Expanded...F21; As regards heating, not only the electric elements and circuitry designs, as such, are covered by subclass Fulltext... Hierarchy... Expanded...H05B, but also the electric aspects of their arrangement, where these concern cases of general application; electric furnaces being considered as such. The physical disposition of the electric elements in furnaces is covered by section F. If a comparison is made with electric welding circuits, which are covered by subclass Fulltext... Hierarchy... Expanded...B23K in connection with welding, it can be seen that electric heating is not covered by the general rule stated in II, above.

|  | H04 |
ELECTRIC COMMUNICATION TECHNIQUE

|  | H04 |
Note(s) This class covers electrical communication systems with propagation paths employing beams of corpuscular radiation, acoustic waves or electromagnetic waves, e.g. radio or optical communication. [4]

|  | H04M |
TELEPHONIC COMMUNICATION (counting mechanisms Fulltext... Hierarchy... Expanded...G06M; circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus Fulltext... Hierarchy... Expanded...G08; reels or other take-up devices for cords Fulltext... Hierarchy... Expanded...H02G 11/00; multiplex transmission between switching centres Fulltext... Hierarchy... Expanded...H04J; selecting arrangements Fulltext... Hierarchy... Expanded...H04Q; loudspeakers, microphones, gramophone pick-ups or like electromechanical transducers Fulltext... Hierarchy... Expanded...H04R)

|  | H04M |
Note(s) This subclass covers: telephonic communication systems combined with other electrical systems; testing arrangements peculiar to telephonic communication systems. In this subclass, the following terms or expressions are used with the meanings indicated: "subscriber" is a general term for terminal equipment, e.g. telephone for public use; "substation" means a subscriber or monitoring equipment which may connect a single subscriber to a line without choice as to subscriber; "satellite" is a type of exchange the operation of which depends upon control signals received from a supervisory exchange; "switching centres" includes exchanges and satellites.

|  | H04M |
Subclass index
TELEPHONIC SYSTEMS |
Combined; party-line systems; prepayment systems | 11/00; 13/00; 17/00
EQUIPMENTS AND ARRANGEMENTS |
Equipments | 1/00
Exchanges: automatic; manual | 3/00; 5/00
Interconnection arrangements: centralised; non-centralised | 7/00; 9/00
Monitoring and control; supply arrangements | 15/00; 19/00
SUBJECT MATTER NOT PROVIDED FOR IN OTHER GROUPS OF THIS SUBCLASS | 99/00

P:70 |  | H04M 1/00 |
Substation equipment, e.g. for use by subscribers (subscriber services or facilities provided at exchanges Fulltext... Hierarchy... Expanded...H04M 3/00; prepayment telephone coin boxes Fulltext... Hierarchy... Expanded...H04M 17/00; current supply arrangements Fulltext... Hierarchy... Expanded...H04M 19/08; keyboard switches in general Fulltext... Hierarchy... Expanded...H01H 13/70, Fulltext... Hierarchy... Expanded...H03K 17/94) [1,7]

|  | H04M 1/02 |
· | Constructional features of telephone sets

|  | H04M 1/03 |
· · | Constructional features of telephone transmitters or receivers, e.g. telephone hand-sets (transducers in general Fulltext... Hierarchy... Expanded...H04R 1/00) [2]

|  | H04M 1/04 |
· · | Supports for telephone transmitters or receivers (for transducers in general Fulltext... Hierarchy... Expanded...H04R 1/00)

|  | H04M 1/05 |
· · · | adapted for use on head, throat, or breast

|  | H04M 1/06 |
· · · | Hooks; Cradles

|  | H04M 1/08 |
· · · · | associated with switches operated by weight of receiver or hand-set

|  | H04M 1/10 |
· · · · | associated with switches operated by magnetic effect due to proximity of receiver or hand-set

|  | H04M 1/11 |
· · | Supports for sets, e.g. incorporating armrests

|  | H04M 1/12 |
· · · | Adjustable supports, e.g. extensible

|  | H04M 1/13 |
· · · · | pantographic

|  | H04M 1/14 |
· · · | with resilient means to eliminate extraneous vibrations

|  | H04M 1/15 |
· · | Protection or guiding telephone cords (devices specially adapted or mounted for storing and repeatedly paying-out and restoring lengths of material Fulltext... Hierarchy... Expanded...B65H 75/34; in general Fulltext... Hierarchy... Expanded...H02G 11/00) [5]

|  | H04M 1/17 |
· · | Hygienic or sanitary devices on telephone equipment (for mouthpieces or earpieces Fulltext... Hierarchy... Expanded...H04R 1/12) [2]

|  | H04M 1/18 |
· · | Telephone sets modified for use in ships, mines, or other places exposed to adverse environment (Fulltext... Hierarchy... Expanded...H04M 1/19 takes precedence; telephone cabinets Fulltext... Hierarchy... Expanded...E04H 1/14)

|  | H04M 1/19 |
· · | Arrangements of transmitters, receivers, or complete sets to prevent eavesdropping, to attenuate local noise or to prevent undesired transmission; Special mouthpieces or receivers therefor (circuit arrangements for preventing eavesdropping Fulltext... Hierarchy... Expanded...H04M 1/68; telephone cabinets Fulltext... Hierarchy... Expanded...E04H 1/14)

|  | H04M 1/20 |
· · | Arrangements for preventing acoustic feedback (Fulltext... Hierarchy... Expanded...H04M 1/62 takes precedence)

|  | H04M 1/21 |
· · | Combinations with auxiliary equipment, e.g. with clock, with memoranda pad

|  | H04M 1/215 |
· · · | by non-intrusive coupling means, e.g. acoustic couplers [7]

|  | H04M 1/22 |
· · | Illuminating; Arrangements for improving visibility of characters on dials

|  | H04M 1/23 |
· · | Construction or mounting of dials or of equivalent devices; Means for facilitating the use thereof (by improving visibility Fulltext... Hierarchy... Expanded...H04M 1/22)

|  | H04M 1/24 |
· | Arrangements for testing (measuring electric values Fulltext... Hierarchy... Expanded...G01R; testing transducers Fulltext... Hierarchy... Expanded...H04R 29/00)

|  | H04M 1/247 |
· | Telephone sets including user guidance or feature selection means facilitating their use [7]

|  | H04M 1/253 |
· | Telephone sets using digital voice transmission (simultaneous speech and data transmission Fulltext... Hierarchy... Expanded...H04M 11/06) [7]

|  | H04M 1/26 |
· | Devices for calling a subscriber (Fulltext... Hierarchy... Expanded...H04M 1/66 takes precedence; coding in connection with keyboards or like devices, in general Fulltext... Hierarchy... Expanded...H03M 11/00) [1,7]

|  | H04M 1/27 |
· · | Devices whereby a plurality of signals may be stored simultaneously [2]

|  | H04M 1/272 |
· · · | with provision for storing only one subscriber number at a time, e.g. by keyboard or dial [2]

|  | H04M 1/274 |
· · · | with provision for storing more than one subscriber number at a time, e.g. using toothed disc [2]

|  | H04M 1/2745 |
· · · · | using static electronic memories, i.e. memories whose operation does not require relative movement between storage means and a transducer, e.g. chip [7]

|  | H04M 1/275 |
· · · · · | implemented by means of portable electronic directories [7]

|  | H04M 1/2755 |
· · · · · | whose contents are provided by optical scanning [7]

|  | H04M 1/276 |
· · · · | using magnetic recording, e.g. on tape [2]

|  | H04M 1/278 |
· · · · | using punched cards or tapes [2]

|  | H04M 1/30 |
· · | Devices which can set up and transmit only one digit at a time

|  | H04M 1/31 |
· · · | by interrupting current to generate trains of pulses; by periodically opening and closing contacts to generate trains of pulses [2]

|  | H04M 1/315 |
· · · · | Clutches, spring assemblies, speed regulators, e.g. centrifugal brakes (Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H04M 1/32-H04M 1/40 take precedence) [3]

|  | H04M 1/32 |
· · · · | Locking setting devices during transmission to prevent interference by user

|  | H04M 1/34 |
· · · · | Lost-motion or other arrangements for ensuring a pause between successive digit transmissions

|  | H04M 1/38 |
· · · · | Pulses transmitted by a movement variably limited by the setting of a stop

|  | H04M 1/40 |
· · · · | wherein the setting-operation short-circuits or open-circuits the transmitting mechanism during a variable part of a cycle

|  | H04M 1/50 |
· · · | by generating or selecting currents of predetermined frequencies or combinations of frequencies [2]

|  | H04M 1/515 |
· · | by generating or selecting other signals than trains of pulses of similar shape or other signals than currents of one or more different frequencies, e.g. generation of dc signals of alternating polarity, coded pulses, impedance dialling [2]

|  | H04M 1/52 |
· · | Arrangements wherein a dial or equivalent is mechanically coupled to a line selector

|  | H04M 1/53 |
· · | Generation of additional signals, e.g. additional pulses [2]

|  | H04M 1/54 |
· · · | Arrangements wherein a dial or equivalent generates identifying signals, e.g. in party-line systems [2]

|  | H04M 1/56 |
· | Arrangements for indicating or recording the called number at the calling subscriber's set

|  | H04M 1/57 |
· | Arrangements for indicating or recording the number of the calling subscriber at the called subscriber's set (at the operator set in a manual exchange Fulltext... Hierarchy... Expanded...H04M 5/20) [2]

|  | H04M 1/58 |
· | Anti-side-tone circuits (hybrid circuits for carrier-frequency operation Fulltext... Hierarchy... Expanded...H04B 1/00)

|  | H04M 1/60 |
· | including speech amplifiers

|  | H04M 1/62 |
· · | Constructional arrangements

|  | H04M 1/64 |
· | Automatic arrangements for answering calls; Automatic arrangements for recording messages for absent subscribers; Arrangements for recording conversations (centralised dictation systems Fulltext... Hierarchy... Expanded...H04M 11/10) [1,7]

|  | H04M 1/65 |
· · | Recording arrangements [2,7]

|  | H04M 1/652 |
· · · | Means for playing back the recorded messages by remote control over a telephone line (Fulltext... Hierarchy... Expanded...H04M 1/658 takes precedence) [7]

|  | H04M 1/654 |
· · · | Telephone line monitoring circuits therefor, e.g. ring detectors [7]

|  | H04M 1/656 |
· · · | for recording conversations [7]

|  | H04M 1/658 |
· · · | Means for redirecting recorded messages to other extensions or equipment [7]

|  | H04M 1/66 |
· | with means for preventing unauthorised or fraudulent calling (verifying user identity or authority in secret or secure digital communications Fulltext... Hierarchy... Expanded...H04L 9/32) [1,7]

|  | H04M 1/663 |
· · | Preventing unauthorised calls to a telephone set [7]

|  | H04M 1/665 |
· · · | by checking the validity of a code [7]

|  | H04M 1/667 |
· · | Preventing unauthorised calls from a telephone set (Fulltext... Hierarchy... Expanded...H04M 1/677 takes precedence) [7]

|  | H04M 1/67 |
· · · | by electronic means [7]

|  | H04M 1/673 |
· · · · | the user being required to key in a code [7]

|  | H04M 1/675 |
· · · · | the user being required to insert a coded card, e.g. a smart card carrying an integrated circuit chip [7]

|  | H04M 1/677 |
· · | Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance [7]

|  | H04M 1/68 |
· | Circuit arrangements for preventing eavesdropping

|  | H04M 1/70 |
· · | Lock-out or secrecy arrangements in party-line systems

|  | H04M 1/72 |
· | Substation extension arrangements; Cordless telephones, i.e. devices for establishing wireless links to base stations without route selecting [1,7]

|  | H04M 1/723 |
· · | using two or more extensions per line (Fulltext... Hierarchy... Expanded...H04M 1/725 takes precedence) [7]

|  | H04M 1/725 |
· · | Cordless telephones [7]

|  | H04M 1/727 |
· · · | Identification code transfer arrangements [7]

|  | H04M 1/73 |
· · · | Battery saving arrangements [7]

|  | H04M 1/733 |
· · · | with a plurality of base stations connected to a plurality of lines [7]

|  | H04M 1/737 |
· · · | characterised by transmission of electromagnetic waves other than radio waves, e.g. infra-red [7]

|  | H04M 1/738 |
· | Interface circuits for coupling substations to external telephone lines (Fulltext... Hierarchy... Expanded...H04M 1/78 takes precedence) [7]

|  | H04M 1/74 |
· · | with means for reducing interference; with means for reducing effects due to line faults

|  | H04M 1/76 |
· · | Compensating for differences in line impedance (in general Fulltext... Hierarchy... Expanded...H04B)

|  | H04M 1/78 |
· | Circuit arrangements in which low-frequency speech signals proceed in one direction on the line, while speech signals proceeding in the other direction on the line are modulated on a high-frequency carrier signal (repeater circuits Fulltext... Hierarchy... Expanded...H04B 3/38) [2]

|  | H04M 1/80 |
· | Telephone line holding circuits [7]

|  | H04M 1/82 |
· | Line monitoring circuits for call progress or status discrimination [7]

P:30 |  | H04M 3/00 |
Automatic or semi-automatic exchanges

|  | H04M 3/02 |
· | Ringing or otherwise calling substations (selective calling Fulltext... Hierarchy... Expanded...H04Q)

|  | H04M 3/04 |
· · | calling signal supplied from final selector

|  | H04M 3/06 |
· · | calling signal supplied from subscriber's line circuit

|  | H04M 3/08 |
· | Indicating faults in circuits or apparatus

|  | H04M 3/10 |
· · | providing fault- or trouble-signals

|  | H04M 3/12 |
· · | Marking faulty circuits "busy"; Enabling equipment to disengage itself from faulty circuits

|  | H04M 3/14 |
· · | Signalling existence of persistent "off-hook" condition

|  | H04M 3/16 |
· | with lock-out or secrecy provision in party-line systems

|  | H04M 3/18 |
· | with means for reducing interference; with means for reducing effects due to line faults

|  | H04M 3/20 |
· | with means for interrupting existing connections; with means for breaking-in on conversations

|  | H04M 3/22 |
· | Supervisory, monitoring, or testing arrangements

|  | H04M 3/24 |
· · | with provision for checking the normal operation

|  | H04M 3/26 |
· · | with means for applying test signals

|  | H04M 3/28 |
· · · | Automatic routine testing

|  | H04M 3/30 |
· · · · | for subscribers' lines

|  | H04M 3/32 |
· · · · | for lines between exchanges

|  | H04M 3/34 |
· · · | Testing for cross-talk (in lines generally Fulltext... Hierarchy... Expanded...H04B)

|  | H04M 3/36 |
· · | Statistical metering, e.g. recording occasions when traffic exceeds capacity of trunks (digital computers for evaluating statistical data Fulltext... Hierarchy... Expanded...G06F 17/18)

|  | H04M 3/38 |
· | Graded-service arrangements, i.e. some subscribers prevented from establishing certain connections (queuing arrangements Fulltext... Hierarchy... Expanded...H04Q 3/64)

|  | H04M 3/40 |
· | Applications of speech amplifiers

|  | H04M 3/42 |
· | Systems providing special services or facilities to subscribers

|  | H04M 3/424 |
· · | Arrangements for automatic redialling (at the subscriber's set Fulltext... Hierarchy... Expanded...H04M 1/27) [7]

|  | H04M 3/428 |
· · | Arrangements for placing incoming calls on hold [7]

|  | H04M 3/432 |
· · | Arrangements for calling a subscriber at a specific time, e.g. morning call service [7]

|  | H04M 3/436 |
· · | Arrangements for screening incoming calls [7]

|  | H04M 3/44 |
· · | Additional connecting arrangements for providing access to frequently-wanted subscribers, e.g. abbreviated dialling (at the subscriber's set Fulltext... Hierarchy... Expanded...H04M 1/27; automatic redialling Fulltext... Hierarchy... Expanded...H04M 3/424) [1,7]

|  | H04M 3/46 |
· · | Arrangements for calling a number of substations in a predetermined sequence until an answer is obtained

|  | H04M 3/48 |
· · | Arrangements for recalling a calling subscriber when the wanted subscriber ceases to be busy

|  | H04M 3/487 |
· · | Arrangements for providing information services, e.g. recorded voice services, time announcement [7]

|  | H04M 3/493 |
· · · | Interactive information services, e.g. directory enquiries [7]

|  | H04M 3/50 |
· · | Centralised arrangements for answering calls; Centralised arrangements for recording messages for absent or busy subscribers (Fulltext... Hierarchy... Expanded...H04M 3/487 takes precedence; centralised dictation systems Fulltext... Hierarchy... Expanded...H04M 11/10) [1,7]

|  | H04M 3/51 |
· · · | Centralised call answering arrangements requiring operator intervention [7]

|  | H04M 3/52 |
· · · · | Arrangements for routing dead number calls to operators

|  | H04M 3/523 |
· · · · | with call distribution or queuing [7]

|  | H04M 3/527 |
· · · | Centralised call answering arrangements not requiring operator intervention [7]

|  | H04M 3/53 |
· · · | Centralised arrangements for recording incoming messages [7]

|  | H04M 3/533 |
· · · · | Voice mail systems [7]

|  | H04M 3/537 |
· · · · | Arrangements for indicating the presence of a recorded message [7]

|  | H04M 3/54 |
· · | Arrangements for diverting calls for one subscriber to another predetermined subscriber

|  | H04M 3/56 |
· · | Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities (video conference systems Fulltext... Hierarchy... Expanded...H04N 7/15)

|  | H04M 3/58 |
· · | Arrangements for transferring received calls from one subscriber to another; Arrangements affording interim conversations between either the calling or the called party and a third party (substation line holding circuits Fulltext... Hierarchy... Expanded...H04M 1/80) [1,7]

|  | H04M 3/60 |
· | Semi-automatic systems, i.e. in which the numerical selection of the outgoing line is under the control of an operator

|  | H04M 3/62 |
· · | Keyboard equipment

|  | H04M 3/64 |
· · | Arrangements for signalling the number or class of the calling line to the operator (between operators in inter-exchange working Fulltext... Hierarchy... Expanded...H04M 5/18)

P:40 |  | H04M 5/00 |
Manual exchanges (substation equipment in general Fulltext... Hierarchy... Expanded...H04M 1/00)

|  | H04M 5/02 |
· | Constructional details (jacks, jack-plugs Fulltext... Hierarchy... Expanded...H01R 24/04)

|  | H04M 5/04 |
· | Arrangements for indicating calls or supervising connections for calling or clearing

|  | H04M 5/06 |
· · | affording automatic call distribution

|  | H04M 5/08 |
· | using connecting means other than cords

|  | H04M 5/10 |
· | using separate plug for each subscriber

|  | H04M 5/12 |
· | Ringing or otherwise calling substations

|  | H04M 5/14 |
· | Applications of speech amplifiers

|  | H04M 5/16 |
· | with means for reducing interference; with means for reducing effects due to line faults

|  | H04M 5/18 |
· | Arrangements for signalling the class or number of called or calling line from one exchange to another

|  | H04M 5/20 |
· · | Number-indicating arrangements for incoming lines

P:50 |  | H04M 7/00 |
Interconnection arrangements between switching centres (transmission arrangements in general Fulltext... Hierarchy... Expanded...H04B)

|  | H04M 7/02 |
· | for compensating differences of ground potential

|  | H04M 7/04 |
· | for compensating differences of line impedance

|  | H04M 7/06 |
· | using auxiliary connections for control or supervision

|  | H04M 7/08 |
· | for phantom working

|  | H04M 7/10 |
· | for two-way working, i.e. calls may be set-up in either direction over the same connection

|  | H04M 7/12 |
· | for working between exchanges having different types of switching equipment, e.g. power-driven and step by step, decimal and non-decimal

|  | H04M 7/14 |
· | in systems involving main and subordinate switching centres (current supply source at subordinate switching centre charged from main exchange Fulltext... Hierarchy... Expanded...H04M 19/06)

|  | H04M 7/16 |
· | in systems employing carrier frequencies

P:60 |  | H04M 9/00 |
Interconnection arrangements not involving centralised switching

|  | H04M 9/02 |
· | involving a common line for all parties

|  | H04M 9/04 |
· | involving a separate line for each pair of parties

|  | H04M 9/06 |
· | involving combinations of interconnecting lines

|  | H04M 9/08 |
· | Two-way loud-speaking telephone systems with means for suppressing echoes or otherwise conditioning for one or other direction of traffic (for line transmission in general Fulltext... Hierarchy... Expanded...H04B 3/20)

|  | H04M 9/10 |
· · | with switching of direction of transmission by voice frequency

P:20 |  | H04M 11/00 |
Telephonic communication systems adapted for combination with other electrical systems

|  | H04M 11/02 |
· | with bell or annunciator systems (such systems in general Fulltext... Hierarchy... Expanded...G08)

|  | H04M 11/04 |
· | with fire, police, burglar, or other alarm systems (such systems in general Fulltext... Hierarchy... Expanded...G08)

|  | H04M 11/06 |
· | Simultaneous speech and telegraphic or other data transmission over the same conductors (transmission of digital information in general Fulltext... Hierarchy... Expanded...H04L)

|  | H04M 11/08 |
· | adapted for optional reception of entertainment or informative matter (systems in which the information is continuously available on a carrier over the whole network Fulltext... Hierarchy... Expanded...H04H 20/81)

|  | H04M 11/10 |
· | with dictation recording and playback systems (such systems in general Fulltext... Hierarchy... Expanded...G11B)

P:80 |  | H04M 13/00 |
Party-line systems (substation equipment Fulltext... Hierarchy... Expanded...H04M 1/00; exchange equipment Fulltext... Hierarchy... Expanded...H04M 3/00, Fulltext... Hierarchy... Expanded...H04M 5/00; metering arrangements Fulltext... Hierarchy... Expanded...H04M 15/36)

P:10 |  | H04M 15/00 |
Metering arrangements; Time-controlling arrangements; Time-indicating arrangements

|  | H04M 15/02 |
· | Severing connection after predetermined time

|  | H04M 15/04 |
· | Recording calls in printed, perforated, or other permanent form

|  | H04M 15/06 |
· · | Recording class or number of calling or of called party

|  | H04M 15/08 |
· | Metering calls to called party

|  | H04M 15/10 |
· | Metering calls from calling party

|  | H04M 15/12 |
· · | Discriminative metering

|  | H04M 15/14 |
· · · | according to class of calling party

|  | H04M 15/16 |
· · · | according to connection obtained

|  | H04M 15/18 |
· · · | according to duration of call

|  | H04M 15/20 |
· · · · | Operator's time recording or indicating arrangements

|  | H04M 15/22 |
· · · | according to time of day

|  | H04M 15/24 |
· · · | preventing metering of tax-free calls to certain lines, e.g. to fire or ambulance stations

|  | H04M 15/26 |
· · | Meter at exchange controlled by operator

|  | H04M 15/28 |
· | with meter at substation

|  | H04M 15/30 |
· · | Meter not controlled from exchange

|  | H04M 15/32 |
· | Metering arrangements for satellites or concentrators which connect one or more exchange lines with a group of local lines

|  | H04M 15/34 |
· | Metering arrangements for private branch exchanges

|  | H04M 15/36 |
· | Metering arrangements for party-lines

|  | H04M 15/38 |
· | Metering by apparatus not of the mechanical step-by-step counter type

P:0 |  | H04M 17/00 |
Prepayment telephone systems (using a coded card to authorise calls from a telephone set Fulltext... Hierarchy... Expanded...H04M 1/675) [1,7]

|  | H04M 17/02 |
· | Coin-freed or check-freed systems (coin-freed or check-freed apparatus in general Fulltext... Hierarchy... Expanded...G07F)

P:90 |  | H04M 19/00 |
Current supply arrangements for telephone systems (for selecting equipment Fulltext... Hierarchy... Expanded...H04Q 1/28)

|  | H04M 19/02 |
· | providing ringing current or supervisory tones, e.g. dialling tone, busy tone

|  | H04M 19/04 |
· · | Ringing-current generated at substation

|  | H04M 19/06 |
· | Current supply source at subordinate switching centre charged from main exchange

|  | H04M 19/08 |
· | Current supply source at substation (battery saving arrangements for cordless telephones Fulltext... Hierarchy... Expanded...H04M 1/73; generating ringing current Fulltext... Hierarchy... Expanded...H04M 19/04) [1,7]

P:100 |  | H04M 99/00 |
Subject matter not provided for in other groups of this subclass [8]