You can connect a standard PC-Headset to the Cisco IP-Phone. The necessary adaptor is described here.

Setup

You need two holes in the case for the 3.5 mm jacks and a hole for the cable. Connect the RJ-/Westernconnector to the phone cable (20 cm should be sufficient). You can also use an old handset cable.

Western-Jack 1 2 3 4
Color (e.g.) black red green yellow
Signal SPK + MIC - MIC + SPK -
Speaker jack L and R ground
Microphone jack ground L and R

Important note: if you find a 2-pin (“mono”) mic connector at your headset, do not connect the contact for the right channel (R, the middle connection). The telephone delivers the usual power supply for an electret microphone and is not compatible with dynamic microphones. If you want to try it anyway, add an capacitor between the mic connection.

Pinout

Here is the pinout for the headset jack at the Cisco phone (the image shows the view upon the jack):

Headset adaptor for Cisco IP phone - 图1

1 2 3 4
SPK+ MIC- MIC+ SPK-

Notes

Also to the earphone jack - instead of the supplied handset - a headset can be connected, z. For example, if the phone does not have a headset jack. However, this jack is different:

The handset jack on the Cisco phone has a different circuitry (the picture shows the top view of the jack):
Headset adaptor for Cisco IP phone - 图2

1 2 3 4
MIC- SPK- SPK+ MIC+