# Common electrical specifications (United States version)

Specification | Description
--- | ---
Connectors | RJ-21x
Return loss (ref. 600 Ohms +2.2 uF standard) | 20 dB min. (ERL)
4 to 2 wire gain Tolerance | +/- 1 dB
4 to 2 wire gain range | +6 to -6 dB
2 to 4 wire gain Tolerance | +/- 1 dB
2 to 4 wire gain range | +6 to -6 dB
Frequency response 300 Hz - 3200 Hz. Reference to 1 kHz | +/- 1 dB
Trans-hybrid loss | 17 dB min. @ 300 Hz-3.0 KHz into 600 Ohms + 2.2 uF
Signal overload level | +3 dBm at 0 dB gain
CMRR | > 80 dB
T-R input impedance (300 - 3200 Hz) | Voice band 600 Ohms +2.2 uF standard
Idle channel noise through connection | < 20 dB rnC
Crosstalk transmit to receive channels | < -70 dB @ 1 kHz
T-R isolation to SELV | >1500VRMS
Off-hook detect | Guaranteed Detect : Current > 10 mA Guaranteed No Detect: Current < 3.3 mA
Operating loop current | 18 mA to 70 mA
Loop current and polarity detect | Single bit indicates if the current is flowing from Tip to Ring or Ring to Tip.
Ring detection | Guaranteed Detect: 30 VRMS 17 - 33 Hz (US version) Guaranteed No Detect: No detect <15 VRMS (0 - 5 kHz)