How to Change the Default LINECODE for a Voice ISDN T1 PRI

D.

In a voice ISDN T1 PRI (Primary Rate Interface) circuit, the digital signal is transmitted as a sequence of 0s and 1s. The line code determines how these 0s and 1s are translated into physical signals that can be transmitted over the physical cabling.

There are four types of line codes used in T1 PRI circuits:

• AMI (Alternate Mark Inversion)
• B8ZS (Bipolar with 8 Zero Substitution)
• HDB3 (High-Density Bipolar with 3 Zeros)
• ESF (Extended Superframe)

Each line code has its own advantages and disadvantages in terms of data integrity, transmission efficiency, and compatibility with different types of equipment.

To change the default line code for a voice ISDN T1 PRI, the administrator should use the "linecode" command followed by the desired line code.

The correct answer to the question is option C, "linecode hdb3". This command sets the line code to High-Density Bipolar with 3 Zeros, which is the default line code for T1 PRI circuits in North America.

Option A, "linecode esf", sets the line code to Extended Superframe, which is an alternative line code for T1 PRI circuits that provides greater reliability and framing flexibility.

Option B, "linecode ami", sets the line code to Alternate Mark Inversion, which is an older line code that is still used in some legacy systems.

Option D, "linecode b8zs", sets the line code to Bipolar with 8 Zero Substitution, which is another alternative line code for T1 PRI circuits that provides greater efficiency and error correction.