Phone Line Specifications
Page 14 of 16 Talk-A-Phone Co.
H. The user is cautioned that any changes or modifications not expressly
approved by the party responsible for compliance could void the user’s
authority to operate the equipment.
I. The Talk-A-Phone Co. U. S. A. Service Center is located at 5013 North Kedzie
Avenue, Chicago, Illinois 60625-4988, telephone number (773) 539-1100, fax
number (773) 539-1241.
IX. Phone Line Specifications
A. MODE I Operation
The following criteria must be met by a phone line to insure proper
functionality of the FCC approved equipment. All voltages use Tip as ground
when measuring.
1. On-Hook voltage must be less than or equal to –36 V (-50 V standard).
2. Off-Hook should be recognized in a maximum time of 300 ms.
3. At an Off-Hook voltage of –15 V, the current that is supplied must be no
less than 20 mA and no more than 120 mA.
4. Dial tone must consist of 350 Hz and 450 Hz tones at –17 dB ± 0.5%.
5. The telephone line must generate Ring-Back consisting of 440 Hz and 480
Hz tones at –17 dB ± 0.5%, with a duty cycle of 1.6 seconds on—4.8 seconds
off ± 10% interrupted at 20 Hz.
6. The telephone line must generate a busy signal consisting of 480 Hz and 620
Hz tones at –17 dB ± 0.5%, with a duty cycle of 500 ms on—500 ms off.
7. The telephone line must be able to recognize or send the following
frequencies in order to decode or transmit DTMF:
a) 685 Hz — 709 Hz Row 1
b) 757 Hz — 784 Hz Row 2
c) 837 Hz — 867 Hz Row 3
d) 925 Hz —957 Hz Row 4
e) 1189 Hz — 1229 Hz Column 1 (1, 4, 7, *)
f) 1314 Hz — 1358 Hz Column 2 (2, 5, 8, 0)
g) 1453 Hz — 1501 Hz Column 3 (3, 6, 9, #)
h) 1607 Hz — 1659 Hz Column 4 (A, B, C, D)
8. When dialing, the telephone line should require a minimum tone pulse ON
time of 40 ms, as well as a minimum between tone gap of 40 ms.
9. The telephone line should support and match with a 600 AC impedance,
as well as a DC resistance of 100 — 200 .
B. MODE II and MODE III Operation
Talk-A-Phone phones can be used with most PBX systems with non-standard
dial tones, ring-backs, busy signals and hang-ups.
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