Meridian Digital Telephones Used With A Headset - Nortel Meridian 1 Manual

Meridian digital telephones Page 17 of 46

Meridian digital telephones used with a headset

You can use an electret headset in the headset port of the digital telephones
(M3310 and M3820 only). Alternatively, choose an amplified headset that
draws power from a battery or AC transformer; power is not provided by the
telephone. The amplifier must draw less than 400 micro amps from the
telephone jack.
The headset should be designed to work with a telephone jack with these
characteristics:
Transmit interface: +5 V through 10K DC bias resistance with maximum
current of 500 micro amps. The differential input impedance is 10K ohms.
Connects to pins 2 and 5 of the headset jack.
Receive interface: single ended output with output impedance of 180 ohms.
Connects to pins 3 and 4 of the headset jack.
Meridian 1 European Digital Telephones