•  MP-124 Rev. D: 
 
 
Warning: For MP-124 Rev. D, routing of FXS telephony cables outdoors can be done 
only in conjunction with AudioCodes’ approved surge protector (Circa model 4B3S-75) 
and proper installation and grounding. When done correctly, the installation will meet 
ITU-T K.21 (basic) standards. For more information, see Section  5.1.1 on page 20. 
 
Figure  5-9: Connecting MP-124 Rev. D to FXS Patch Panel