Sec. 90.483  Permissible methods and requirements of interconnecting 
          private and public systems of communications.

    Interconnection may be accomplished by commercial mobile service 
providers licensed under this part by any technically feasible means. 
Interconnection may be accomplished by private mobile service providers 
either manually or automatically under the supervision and control of a 
transmitter control operator at a fixed position in the authorized 
system of communications or it may be accomplished under the supervision 
and control of mobile operators, and is subject to the following 
provisions:
    (a) Where a system is interconnected manually at a fixed control 
point, the control point operator must maintain the capability to turn 
the carrier of the transmitter off or to de-activate the system 
completely when circumstances warrant such action.
    (b) When the system is interconnected automatically it may be 
supervised at the control point or in mobile units.
    (1) For control point supervision, the following is required:
    (i) The control point operator must maintain the capability to turn 
the carrier of the transmitter off or to de-activate the system 
completely when circumstances warrant such action.
    (ii) When a frequency is shared by more than one system, automatic 
monitoring equipment must be installed at the base station to prevent 
activation of the transmitter when signals of co-channel stations are 
present and activation would interfere with communications in progress. 
Licensees may operate without the monitoring equipment if they have 
obtained the consent of all co-channel licensees located within a 120 km 
(75 mile) radius of the interconnected base station transmitter. A 
statement must be submitted to the Commission indicating that all co-
channel licensees have consented to operate without the monitoring 
equipment. If a licensee has agreed that the use of monitoring equipment 
is not necessary, but later decides that the monitoring equipment is 
necessary, the

[[Page 521]]

licensee may request that the co-channel licensees reconsider the use of 
monitoring equipment. If the licensee cannot reach an agreement with co-
channel licensees, the licensee may request that the Commission consider 
the matter and assign it to another channel. If a new licensee is 
assigned to a frequency where all the co-channel licensees have agreed 
that the use of monitoring equipment is not necessary, and the new 
licensee does not agree, the new licensee may request the co-channel 
licensees to reconsider the use of monitoring equipment. If the new 
licensee cannot reach an agreement with co-channel licensees, it should 
request a new channel from the Commission. Systems on frequencies above 
800 MHz are exempt from this requirement.
    (2) For mobile unit supervision, the following is required:
    (i) When a frequency is shared by more than one system, automatic 
monitoring equipment must be installed at each base station to prevent 
its activation when signals of other co-channel stations are present and 
activation would interfere with communications in progress. Licensees 
may operate without this equipment if they have obtained the consent of 
all co-channel licensees located within a 120 km (75 mile) radius of the 
interconnected base station transmitter. A statement must be submitted 
to the Commission indicating that all co-channel licensees have 
consented to operate without the monitoring equipment. If a licensee has 
agreed that the use of monitoring equipment is not necessary, but later 
decides that the monitoring equipment is necessary, the licensee may 
request that the co-channel licensees reconsider the use of monitoring 
equipment. If the licensee cannot reach an agreement with co-channel 
licensees, the licensee may request that the Commission consider the 
matter and assign it to another channel. If a new licensee is assigned 
to a frequency where all the co-channel licensees have agreed that the 
use of monitoring equipment is not necessary, and the new licensee does 
not agree, the new licensee may request the co-channel licensees to 
reconsider the use of monitoring equipment. If the new licensee cannot 
reach an agreement with co-channel licensees, it should request a new 
channel from the Commission. Systems above 800 MHz are exempt from this 
requirement.
    (ii) Initial access from points within the public switched telephone 
network must be limited to transmission of a 3-second tone, after which 
time the transmitter shall close down. No additional signals may be 
transmitted until acknowledgement from a mobile station of the licensee 
is received. Licensees are exempt from this requirement if they have 
obtained the consent of all co-channel licensees located within a 120 km 
(75 mile) radius of the interconnected base station transmitter. 
However, licensees may choose to set their own time limitations. A 
statement must be submitted to the Commission indicating that all co-
channel licensees have consented to operate without the monitoring 
equipment. If a licensee has agreed that the use of monitoring equipment 
is not necessary, but later decides that the monitoring equipment is 
necessary, the licensee may request that the co-channel licensees 
reconsider the use of monitoring equipment. If the licensee cannot reach 
an agreement with co-channel licensees, the licensee may request that 
the Commission consider the matter and assign it to another channel. If 
a new licensee is assigned to a frequency where all the co-channel 
licensees have agreed that the use of monitoring equipment is not 
necessary, and the new licensee does not agree, the new licensee may 
request the co-channel licensees to reconsider the use of monitoring 
equipment. If the new licensee cannot reach an agreement with co-channel 
licensees, it should request a new channel from the Commission. Systems 
above 800 MHz are exempt from this requirement.
    (c) In single frequency systems, equipment must be installed at the 
base station which will limit any single transmission from within the 
public switched telephone network to 30 seconds duration and which in 
turn will activate the base station receiver to monitor the frequency 
for a period of not less than three (3) seconds. The mobile station must 
be capable of terminating the communications during the three (3) 
seconds. Licensees are exempt

[[Page 522]]

from this requirement if they have obtained the consent of all co-
channel licensees located within a 120 km (75 mile) radius of the 
interconnected base station transmitter. However, licensees may choose 
to set their own time limitations. A statement must be submitted to the 
Commission indicating that all co-channel licensees have consented to 
operate without the monitoring equipment. If a licensee has agreed that 
the use of monitoring equipment is not necessary, but later decides that 
the monitoring equipment is necessary, the licensee may request that the 
co-channel licensees reconsider the use of monitoring equipment. If the 
licensee cannot reach an agreement with co-channel licensees, the 
licensee may request that the Commission consider the matter and assign 
it another channel. If a new licensee is assigned to a frequency where 
all the co-channel licensees have agreed that the use of monitoring 
equipment. If the new licensee cannot reach an agreement with co-channel 
licensees, it should request a new channel from the Commission.
    (d) A timer must be installed at the base station transmitter which 
limits communications to three (3) minutes. After three (3) minutes, the 
system must close down, with all circuits between the base station and 
the public switch telephone network disconnected. This provision does 
not apply to systems which establish eligibility pursuant to 
Secs. 90.20(a)(1)(i), 90.20(a)(1)(ii), and 90.20(a)(2), except 
Secs. 90.20(a)(2)(i) and 90.20(a)(2)(ii), or who are Power, Petroleum, 
or Railroad licensees (as defined in Sec. 90.7), or to systems above 800 
MHz. All systems must be equipped with a timer that closes down the 
transmitter within three minutes of the last transmission. Licensees may 
operate without these requirements if they have obtained the consent of 
all co-channel licensees located within a 120 km (75 mile) radius of the 
interconnected base station transmitter. However, licensees may choose 
to set their own time limitations. A statement must be submitted to the 
Commission indicating that all co-channel licensees have consented to 
operate without the monitoring equipment. If a licensee has agreed that 
the use of monitoring equipment is not necessary, but later decides that 
the monitoring equipment is necessary, the licensee may request that the 
co-channel licensees reconsider the use of monitoring equipment. If the 
licensee cannot reach an agreement with co-channel licensees, the 
licensee may request that the Commission consider the matter and assign 
it to another channel. If a new licensee is assigned to a frequency 
where all the co-channel licensees have agreed that the use of 
monitoring equipment is not necessary, and the new licensee does not 
agree, the new licensee may request the co-channel licensees to 
reconsider the use of monitoring equipment. If the new licensee cannot 
reach an agreement with co-channel licensees, it should request a new 
channel from the Commission.
[ 47 FR 17520 , Apr. 23, 1982, as amended at  48 FR 29518 , June 27, 1983; 
 50 FR 15153 , Apr. 17, 1985;  58 FR 44961 , Aug. 25, 1993;  59 FR 59966 , 
Nov. 21, 1994;  61 FR 6576 , Feb. 21, 1996;  62 FR 18934 , Apr. 17, 1997]

    Effective Date Note: At  62 FR 18934 , Apr. 17, 1997, Sec. 90.483 was 
amended by revising the third sentence of paragraph (d), effective Oct. 
17, 1997.

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