| 1: | What is the scope of the I.431 and I.432 standards? |
| A1: | I.431 defines the Primary Rate Interface, and I.432 defines the Basic Rate Interface. |
| 2: | Where does the name D channel come from? What are the operational speeds of the D channel for BRI and PRI? |
| A2: | The name D channel comes from Delta. It operates at 16 kbps for BRI and 64 kbps for PRI . |
| 3: | What is a V-reference point in ISDN? |
| A3: | A V-reference point defines the interface in a Local Exchange (LE) between the Local Termination (LT) and Exchange Termination (ET). |
| 4: | What are the important pins in a S/T interface? |
| A4: | 3, 4, 5, and 6. |
| 5: | What is the modulation of the ISDN U-interface? |
| A5: | The U-Interface uses frequency-division multiplexing and echo cancellation. |
| 6: | What is the bit rate of the S/T interface and U-interface? |
| A6: | S/T interface192 kbps; U-interface160 kbps. |
| 7: | How many INFO messages participate in the BRI's Layer 1 initialization? What does INFO0 mean? |
| A7: | INFO0 to INFO4; INFO0 means "no signal." |
| 8: | Which bit in the ISDN frame indicates line activation? |
| A8: | The A bit set to 1 indicates the activation of the line. |
| 9: | What makes up DLCI in ISDN? What is the length of DLCI, TE, and SAPI? |
| A9: | TEI and SAPI in the LAPD protocol represent the 13-bit data-link connection identifier ( DLCI ). TEI is 7 bits; SAPI is 6 bits. |
| 10: | What are the two indicators that Layer 2 is active? |
| A10: | Receiving a UA message with SAPI = 0 or TEI = xxx , where xxx is not 0 or 127. |
| 11: | What does TE = 127 mean? |
| A11: | TEI = 127 is a broadcast. |
| 12: | What is the dynamic range of TEI? |
| A12: | TEI ranges from 64126. |
| 13: | What does SAPI = 0 indicate ? |
| A13: | Call control procedure. |
| 14: | How do you distinguish an incoming from an outgoing call? |
| A14: | Check the reference flag in the Q.931 message. A message of 0 is sent by the call originator, and 1 means that the message was sent by the other party. |
| 15: | Which ISDN protocol provides information about Bearer capability. Name three basic types of Bearer capabilities. |
| A15: | Bearer capability is part of the format of the ISDN Q.931 protocol, which provides information for the type of the call56-kbps data, 64-kbps data, or 56-kbps voice. |
