JK Audio innkeeper PBX - Manual (Page 13)

A-B-C Selector Switch
Use this switch to select the correct type of handset microphone your telephone
uses. A=Electret, B=Carbon, C=Dynamic. Trial and error seems to work best in
determining which handset type to use. Your innkeeper PBX will only function
correctly if the handset type selector switch is in the correct position. This switch
changes signal level, impedance, and wiring to accommodate the differences
in handset microphone types. To determine the correct position, you should
place a call to another telephone line, then try to send audio to the phone line
through the input jack of the innkeeper PBX . While doing this, switch between
the three different handset type positions. Choose the position that works best by
monitoring the audio quality and Send LEDs.
Although not conclusive, the following guidelines may help:
• The majority of newer telephones have electret type microphones and will use
the ‘A’ position.
• Older telephones that have the round “screw type” handsets contain carbon
microphones and use the ‘B’ position.
• Many Radio Shack®, Panasonic®, and Nortel® telephones have dynamic
microphone types and use the ‘C’ position.
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Configuration
Configuration