|Article ID: 1570|
Configuring the DSU IV ESP for ISDN Dial Backup (DBU)
Q: Configuring the DSU IV ESP for ISDN Dial Backup (DBU)
This document outlines how to configure the ISDN dial backup functions of the DSU IV ESP. In this document, the term HOST will apply to the local unit that is dialing out. The term REMOTE will refer to the unit that is being dialed.
Before you Begin
Order your ISDN service per the DSU IV ESP User Manual. It can be found before the table of contents and is titled ISDN Service Ordering Information for the ADTRAN DSU IV ESP with ISDN Dial Backup. If your Telephone Company supports ISDN Ordering Codes, you may want to request IOC B1. For more information, see KB Article # 1596.
You will need the following information from the Telephone Company providing your ISDN service:
- Service Profile Identifier (SPID)
- Switch type
Setting up the DSU for ISDN Dial Backup
- The ISDN Dial Backup card must be configured for the ISDN line. The menu path to program the SPID is CONFIG->LOCAL->DIAL OPTIONS->PHONE_NUMBERS.
- Select STORED NUMBER TO EDIT 1 and enter the remote number that you will be dialing.
- Select STORED NUMBER TO EDIT 9 and enter the host SPID.
- Select STORED NUMBER TO EDIT 10 and enter the host seven digit Local Directory Number.
- Configure the ISDN DBU options found at CONFIG->LOCAL->DIAL OPTIONS->DBU OPTIONS.
- Option 1 is AUTOMATIC DBU. Set to ENABLED.
- Option 2 is NUMBER TO DIAL. Set HOST side to DBU WITH #1.
- Option 3 is ORIGIN/ANSWER. Set the HOST side to DBU ORIGINATE. Set the REMOTE side to DBU ANSWER.
- Option B is the SWITCH TYPE. Select the correct Switch Type as provided by your Telephone Company.
- Option C is the DTE PROTOCOL. Choose V.120.
Verifying the ISDN Dial Backup
To verify that the ISDN line is configured correctly, go to STATUS and arrow down to ISDN DBU STATUS. Check for the following messages:
- IDLE - This is normal. Messages are not being transmitted but the ISDN service is ready and immediately available for dialing.
- IN DIAL BACKUP - The DSU IV ESP is currently in dial backup mode.
- NO RX SIGNAL - Indicates the ISDN line is inactive. The ISU card does not recognize a valid ISDN signal. First, make sure the ISDN line is securely attached to the ESP ISDN jack on the back of the DSU. If this does not change the message, then try changing the cable with a regular (RJ11 to RJ11) telephone cable. If this does not fix the problem, then contact the Telephone Company to verify they have turned on the circuit.
- GETTING TEI - The ISU card is getting the first terminal endpoint identifier from the Telephone Company. Make sure the SPID and SWITCH TYPE above are correct. Try choosing NATIONAL ISDN as the Switch Type. If that does not work, then contact the Telephone Company.
- REGISTER SPID - The ISU card is registering the SPID with the Telephone Company. Make sure the SPID and SWITCH TYPE above are correct. Try choosing NATIONAL ISDN as the Switch Type. If that does not work, then contact the Telephone Company.
You can test the ISDN connection using the following menu path: TEST->DBU CONNECTION->DIAL STORED #, then choose STORED NUMBER 1. The host unit should dial and connect to the remote site. If this does not work, see the possible problems and corrective actions listed below:
- Remote side not set up correctly - Verify the remote site shows ISDN DBU STATUS IDLE. Otherwise, troubleshoot the remote ISDN configuration.
- No long distance service - If the remote unit is not in the local area, it is possible that the host ISDN line has not been provisioned with a long distance service. Contact the Telephone Company.
- Protocol mismatch - Verify both sides are set to V.120 protocol.