28 | Section 4
e internal DIP switch bank is divided up into two subsets of 4 switches each:
♦ Bits #1 through 4 congure the Hx’s telephone interface circuitry to match the telephone
line impedance and voltage characteristics of the country where the hybrid is used.
♦ Bits #5 through 8 congure Call Progress Tone Detection to match the call progress
tones used by various countries or central oce switches. Call progress tones (Dial tone,
busy tone, etc) can be used to make the Hx disconnect when loop current signaling is not
available or is unreliable. Call Progress Tone Disconnect is active only on Auto-Answered
incoming calls to prevent undesired disconnections. It may be disabled if the feature
causes problems in your application. See internal DIP switch settings table below.
Table 1 lists what telephone network characteristics are being selected by Bits #1 through 4.
Table 2 lists the Call Progress Tone Detection characteristics being selected by Bits #5 through 8.
Table 3 lists the recommended DIP switch settings for each country. Reorder tone is a “fast
busy” signal often used to indicate network congestion or error conditions.
Table 1 - Internal DIP Switch bank
Bit 1 Bit 2 Bit 3 Bit 4 Telephone Network
OFF OFF OFF OFF USA, Canada
OFF OFF OFF ON Japan, low voltage networks
OFF OFF ON OFF FCC compliant countries
OFF OFF ON ON CRT21, Europe (real line impedance)
OFF ON OFF OFF Custom country conguration
OFF ON OFF ON Custom country conguration
OFF ON ON OFF Custom country conguration
OFF ON ON ON Europe (complex line impedance)
ON OFF OFF OFF Custom country conguration
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