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Typical Measurements on a POTS Line
Generally Accepted Criteria of Plain Old Telephone
Service (POTS) service (US and Canada):
Parameter
Acceptable
Marginal
Unacceptable
Current
> 23
20 to 23
< 20 mA
Loss
< 8.5
--
> 8.5 dBm
Noise
< 20
20 to 30
> 30 dBrnC
<-70
-70 to -60
>-60 dBm0p
Power Inf.
< 80
80 to 90
> 90 dBrnC
<-10
-10 to 0
> 0 dBm0p
Ground Res. * < 25
--
> 25 Ohms
Insulation Res.> 3M
3k to 3M
< 3k Ohms
Balance.
>59
50 to 59
< 50 dB
* Note: Ground Resistance can not be measured on
“floating tip” or “floating A” switches such as the AT&T
#5ESS.
