Sec. 68.314  Billing protection.

    (a) Call duration requirements on data equipment connected to the 
public switched network, or to tie trunks, or to private lines that 
access the public switched network. Registered data terminal equipment 
and registered protective circuitry shall comply with the following 
requirements when answering an incoming call, except in off-hook states 
in which the signals are transmitted and/or received by electroacoustic 
transducers only:

    Note:  This paragraph (a) will be applicable to terminal equipment 
and registered protective circuitry employed with digital services where 
such digital services are interconnected with the analog telephone 
network.

    (1) Registered protective circuitry. Registered protective circuitry 
connected to associated data equipment shall assure that the following 
signal power limitations are met for at least 2 seconds after the off-
hook condition is presented to the telephone network in response to an 
incoming call:
    (i) Signals that appear at the protective circuitry/telephone 
network interface for delivery to the telephone network shall be limited 
to -55 dB with respect to one milliwatt as such signals are delivered 
into a loop simulator circuit or a 600 ohm termination, as appropriate; 
and
    (ii) Signals that appear at the protective circuitry-associated data 
equipment interface for delivery to associated data equipment shall be 
limited as follows: for any received signal power (appearing at the 
protective circuitry-telephone network interface) up to 0 dB with 
respect to one milliwatt (at any frequency in the range of 200 to 3200 
Hertz), the power of signals delivered to associated data equipment 
shall be no greater than the signal power that would be delivered as a 
result of received signal power of -55 dB with respect to one milliwatt.
    (2) Registered terminal equipment. Registered terminal equipment for 
data applications shall assure that, when an incoming telephone call is 
answered, the answering terminal equipment prevents both transmission 
and reception of data for at least 2 seconds after the answering 
terminal equipment transfers to the off-hook condition. For the purpose 
of this requirement, a fixed sequence of signals that is transmitted 
(and originated within) and/or received by the registered terminal 
equipment each time it answers an incoming call shall not be considered 
data, provided that such signals are for one or more of the following 
purposes:
    (i) Disabling echo control devices,
    (ii) Adjusting automatic equalizers and gain controls,
    (iii) Establishing synchronization, or
    (iv) Signaling the presence and if required, the mode of operation, 
of the data terminal at the remote end of a connection.
    (b) Voice and data equipment on-hook signal requirements for 
equipment connected to the public switched network, or

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to tie trunks, or to private lines that access the public switched 
network. Registered protective circuitry and registered terminal 
equipment shall comply with the following:
    (1) The power delivered into a 2-wire loop simulator circuit or into 
the transmit and receive pairs of a 4-wire loop simulator or into a 600 
ohm termination (where appropriate) in the on-hook state, by loop-start 
or ground-start equipment shall not exceed -55dB with respect to one 
milliwatt within the frequency band from 200 to 4000 Hertz. Registered 
protective circuitry shall also assure that for any input level up to 
10dB above the maximum level that is expected under normal operation, 
the power to a 2-wire loop simulator circuit or the transmit and receive 
pairs of a 4-wire loop simulator circuit or into a 600 ohm termination 
(where appropriate) does not exceed the above limits.
    (2) The power delivered into a 2-wire loop simulator circuit or into 
the transmit and receive pairs of a 4-wire loop simulator circuit, in 
the on-hook state, by reverse battery equipment shall not exceed -55dB 
with respect to one milliwatt, unless the equipment is arranged to 
inhibit incoming signals.
    (c) Voice and data equipment loop current requirements for equipment 
connected to the Public Switched network. The loop current through 
registered terminal equipment or registered protective circuitry, when 
connected to a 2-wire or 4-wire loop simulator circuit with the 600 ohm 
resistor and 500 microfarad capacitor of the 2-wire loop simulator 
circuit or both pairs of the 4-wire loop simulator circuit disconnected 
shall, for at least 5 seconds after the equipment goes to the normal 
off-hook state which would occur in response to ringing (called party 
condition):
    (1) Be at least as great as the current obtained in the same loop 
simulator circuit with a 200 ohm resistance connected across the tip and 
ring of the 2-wire loop simulator circuit or connected across the tip/
ring and tip 1/ring 1 conductors (tip and ring connected together and 
tip 1 and ring 1 connected together) of the 4-wire loop simulator 
circuit in place of the registered terminal equipment or registered 
protective circuitry; or
    (2) Not decrease by more than 25 percent from its maximum value 
attained during this 5-second interval; unless the equipment is returned 
to the on-hook state during the above 5 second interval.
    (d) Signaling interference requirements. (1) Terminal equipment 
connected to the Public Switched Network or private lines identified in 
Sec. 68.2(a) (2) and (3). Registered terminal equipment and registered 
protective circuitry shall not deliver signals into a 2-wire loop 
simulator circuit or the transmit and receive pairs of a 4-wire loop 
simulator circuit or a 600-ohm termination (where appropriate) from 
sources internal to the registered equipment or circuitry, with energy 
in the 2450 to 2750 Hertz band unless an equal amount of energy is 
presented in the 800 to 2450 Hertz band.
    (2) Registered terminal equipment for connection to subrate or 1.544 
Mbps digital services shall not deliver digital signals to the telephone 
network with encoded analog content energy in the 2450 to 2750 Hertz 
band unless at least an equal amount of encoded analog energy is present 
in the 800 to 2450 Hertz band.
    (e) Operating requirements for automatic identified outward 
dialing--(1) General. Registered terminal equipment that provides 
Automatic Identified Outward Dialing (AIOD) features shall meet those 
operating requirements necessary to ensure compatibility with the local 
telephone company serving central office. A sufficient set of operating 
characteristics for interfacing with central office AIOD channels is 
contained in the Electronics Industries Association (EIA) Standard RS-
464, Section 4.4.1., dated December 1979.
    (2) Station number assignment. Station number assignments in 
registered terminal equipment with AIOD capabilities, including spare 
numbers for subsequent activities by the customer, must be programed 
into the equipment by a qualified installer only and such numbers must 
be restricted to the group of station numbers provided by the telephone 
company. If the registered terminal equipment is arranged so that

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the customer can reassign and/or activate new station numbers, means 
shall be provided so that the customer can verify that the 4-digit 
number assigned to a station set, incoming tie trunk, or the attendant 
for AIOD purposes is the same as the number identified by the registered 
terminal equipment for AIOD when an outgoing call to a central office is 
originated.
    (f) On-hook signal requirements for registered terminal equipment 
for connection to subrate or 1.544 Mbps digital services. Registered 
terminal equipment and registered protective circuitry shall comply with 
the following:
    (1) The power delivered to the telephone network in the on-hook 
state as derived by a zero level decoder shall not exceed -55 dBm 
equivalent power for digital signals within the frequency band from 200 
to 4000 Hertz. Registered protective circuitry shall also assure that 
for any input level up to 10 dB above the maximum level that is expected 
under normal operation, the power to a zero level decoder does not 
exceed the above limits.
    (2) The power derived by a zero level decoder, in the on-hook state, 
by reverse battery equipment shall not exceed -55 dB with respect to one 
milliwatt, unless the equipment is arranged to inhibit incoming signals.
    (g) Off-hook signal requirements for registered terminal equipment 
connecting to 1.544 Mbps digital services. Upon entering the normal off-
hook state, in response to alerting, for analog subrate channels, 
registered terminal equipment shall continue to transmit the signaling 
bit sequence representing the off-hook state for 5 seconds, unless the 
equipment is returned to the on-hook state during the above 5 second 
interval.
    (h) Operating Requirements for Direct-Inward-Dialing (``DID''). (1) 
Answer supervision for DID calls to stations connected to the telephone 
company network through a Private Branch Exchange or similar system 
(``PBX'') shall be returned to the central office on all calls which 
are:
    (i) Answered by the called DID station,
    (ii) Answered by an attendant,
    (iii) Routed to an announcement, except for ``number invalid,'' 
``not in service,'' or ``not assigned'' recordings,
    (iv) Routed to a dialing prompt, or
    (v) Routed back to the public switched network by the PBX, including 
calls routed to ``number invalid,'' ``not in service,'' or ``not 
assigned'' recordings.
    (2) DID calls which do not require the PBX to return answer 
supervision are those:
    (i) Which are not routed back to the public switched network and, in 
addition, are:
    (A) Unanswered, i.e., the called DID station receives a ring or 
other alerting signal, but does not answer, or the DID station to which 
the call is forwarded receives a ring or other alerting signal, but does 
not answer,
    (B) Routed to a busy signal,
    (C) Routed to a reorder signal, or
    (D) Routed to a recorded announcement stating ``number invalid,'' 
``not in service,'' or ``not assigned''; and those
    (ii) Which are routed back to the public switched network and, in 
addition, are:
    (A) Unanswered, i.e., the called station receives a ring or other 
alerting signal, but does not answer, or the DID station to which the 
call is forwarded receives a ring or other alerting signal, but does not 
answer,
    (B) Routed to a busy signal, or
    (C) Routed to a reorder signal.
    (3) Answer supervision on DID calls shall be provided in accordance 
with industry engineering standards.
    (4) PBX and similar systems manufactured one year from December 31, 
1990, shall comply with the paragraph. PBX and similar systems of 
earlier manufacture shall comply with the paragraph if newly installed 
or relocated on a customer's premises eighteen months from December 31, 
1990, or any time thereafter. Such equipment must be reregistered by the 
manufacturer or other person responsible for equipment compliance with 
part 68, if already registered but not compliant with this paragraph 
(h). Compliance with the paragraph shall require that the equipment be 
designed, manufactured and installed so that it will return answer 
supervision in conformity

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with this rule in a manner which cannot be readily altered by software 
control or other user controlled media.
    (5) As used in this Sec. 68.314(h), Private Branch Exchange or 
similar system (``PBX'') means customer premises equipment, such as 
private branch exchanges, key equipment, multifunction systems, 
multiplexers, and any equipment for which adopted industry standard 
signalling is the standard mode of returning answer supervision.

[ 45 FR 20853 , Mar. 31, 1980, as amended at  47 FR 10219 , Mar. 10, 1982; 
 47 FR 39687 , Sept. 9, 1982;  47 FR 42750 , Sept. 29, 1982;  49 FR 48725 , 
Dec. 14, 1984;  50 FR 27251 , July 2, 1985;  51 FR 950 , Jan. 9, 1986;  51 FR 16690 , May 6, 1986;  55 FR 46066 , Nov. 1, 1990]