Phone-Jack Choice Affects Modem Performance

Permissive and data phone jacks are specified by the FCC Rules and Regulations, Part 68, for connection to the public switched telephone system. Permissive jacks are satisfactory for low data transmission speeds and strong telephone signals but data jacks should be considered for transmission speeds over 2400 bits per second and areas of weak and noisy signals. The article illustrates the two jack type connections and suggests solutions to problems the from using exclusion key telephones and various branch exchanges. CAPTION: (Phone jack arrangements).