[asterisk-users] ISDN config: LBO values

[Jaap Winius]

Hi all,

When configuring Asterisk with an ISDN card, it will at one point  
become necessary to select the LBO (Line Build-Out) value. This is an  
integer (0-7) that is determined by the length of the cable and is  
selected from the following table. Many of us are familiar with it:

         CSU (dB)   DSX-1 (feet)
    -------------------------------
    0    0          0?133
    1               133?266
    2               266?399
    3               399?533
    4               533?655
    5    -7.5
    6    -15
    7    -22.5

The value selected should almost always be zero. However, if the cable  
is of a significant length, another value must be selected, but which  
one? There are two columns: CSU and DSX-1. When is it appropriate to  
use the one or the other to determine the correct LBO value?

Thanks,

Jaap