Motorola MOC4600i Installation And Programming Instructions page 13

Device Operation
Mount the device in a vertical position. The recommended mounting height is 48
inches from the floor. When recording your messages on the MOC, the
recommended distance from the device to the lips is two to three inches (5.0 to
7.5 cm). Not performing this accurately may result in audio distortion.
Electromagnetic Interference/Compatibility
Note: Nearly every electronic device is susceptible to electromagnetic
interference (EMI) if inadequately shielded, designed or otherwise
configured for electromagnetic compatibility.
Facilities
To avoid electromagnetic interference and/or compatibility conflicts, do not use
this device where posted notices instruct you not to do so. Hospitals or healthcare
facilities may be using equipment that is sensitive to external RF energy.
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