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# Troubleshooting

This appendix contains the following sections:

ISDN cause codes
Common problems and their solutions A-7

## ISDN cause codes

ISDN cause codes are numerical diagnostic codes sent from an ISDN switch to a DTE. These codes provide an indication of why a call failed to be established or why a call terminated. The cause codes are part of the ISDN D-channel signaling communications supported by the Signaling System 7 supervisory network (WAN). When you dial an ISDN call from the MAX, the MAX reports the cause codes in the Message Log status menu. When the MAX clears the call, a cause code is reported even if inband signaling is in use. If the PRI or BRI switch type is 1TR6 (Germany), see Table A-2.

Table A-1 lists the numeric cause codes and provides a description of each.

Table A-1. ISDN cause codes

#### Code

#### Cause

0

Valid cause code not yet received

1

Unallocated (unassigned) number

2

No route to specified transit network (WAN)

3

No route to destination

4

Send special information tone

5

Misdialed trunk prefix

6

Channel unacceptable

7

Call awarded and being delivered in an established channel

8

Prefix 0 dialed but not allowed

9

Prefix 1 dialed but not allowed

10

Prefix 1 dialed but not required

11

More digits received than allowed, but the call is proceeding

16

Normal clearing

17

User busy

18

No user responding

19

No answer from user (user alerted)

21

Call rejected

22

Number changed

23

Reverse charging rejected

24

Call suspended

25

Call resumed

26

Nonselected user clearing

27

Destination out of order

28

Invalid number format (incomplete number)

29

Facility rejected

30

Response to STATUS ENQUIRY

31

Normal, unspecified

33

Circuit out of order

34

No circuit/channel available

35

Destination unattainable

37

Degraded service

38

Network (WAN) out of order

39

Transit delay range cannot be achieved

40

Throughput range cannot be achieved

41

Temporary failure

42

Switching equipment congestion

43

Access information discarded

44

Requested circuit channel not available

45

Pre-empted

46

Precedence call blocked

47

Resource unavailable, unspecified

49

Quality of service unavailable

50

Requested facility not subscribed

51

Reverse charging not allowed

52

Outgoing calls barred

53

Outgoing calls barred within Call User Group (CUG)

54

Incoming calls barred

55

Incoming calls barred within CUG

56

Call waiting not subscribed

57

Bearer capability not authorized

58

Bearer capability not presently available

63

Service or option not available, unspecified

65

Bearer service not implemented

66

Channel type not implemented

67

Transit network selection not implemented

68

Message not implemented

69

Requested facility not implemented

70

Only restricted digital information bearer capability is available

79

Service or option not implemented, unspecified

81

Invalid call reference value

82

Identified channel does not exist

83

A suspended call exists, but this call identity does not

84

Call identity in use

85

No call suspended

86

Call having the requested call identity has been cleared

87

Called user not member of CUG

88

Incompatible destination

89

Nonexistent abbreviated address entry

90

Destination address missing, and direct call not subscribed

91

Invalid transit network selection (national use)

92

Invalid facility parameter

93

Mandatory information element is missing

95

Invalid message, unspecified

96

Mandatory information element is missing

97

Message type nonexistent or not implemented

98

Message not compatible with call state, or message type nonexistent or not implemented

99

Information element nonexistent or not implemented

100

Invalid information element contents

101

Message not compatible with call state

102

Recovery on timer expiry

103

Parameter nonexistent or not implemented, passed on?

111

Protocol error, unspecified

127

Internetworking, unspecified

Table A-2. ISDN cause codes for 1TR6 switch type

#### 1TR6 Code | #### Cause
--- | ---
1 | Invalid call reference value.
3 | Bearer service not implemented. (Service not available in the A-exchange or at another position in the network, or no application has been made for the specified service.)
7 | Call identity does not exist. (Unknown call identity).
8 | Call identity in use. (Call identity has already been assigned to a suspended link.)
10 | No channel available. (No useful channel available on the subscriber access line-only local significance.)
16 | Requested facility not implemented. (The specified FAC code is unknown in the A-exchange or at another point in the network.)
17 | Request facility not subscribed. (Request facility rejected because the initiating or remote user does not have appropriate authorization.)
32 | Outgoing calls barred. (Outgoing call not possible because of access restriction that has been installed.)
33 | User access busy. (If the total made up of the number of free B channels and the number of calling procedures without any defined B channel is equal to four, any new incoming calls will be rejected from within the network. The calling party receives a DISC with a cause `user access busy`, which indicates the first busy instance, and a busy signal.)
34 | Negative CUG comparison. (Link not possible because of negative CUG comparison.)
35 | Nonexistent CUG. (This CUG does not exist.)
37 | Communication as semipermanent link not permitted.
48 - 50 | Not used. (Link not possible because, for example, RFNR check is negative.)
53 | Destination not obtainable. (Link cannot be established in the network because of incorrect destination address, services, or facilities.)
56 | Number changed. (Number of B-subscriber has changed.)
57 | Out of order. (Remote TE not ready.)
58 | No user responding. (No TE has responded to the incoming SETUP or call has been interrupted, absence assumed-expiry of call timeout T3AA.)
59 | User busy. (B-subscriber busy)
61 | Incoming calls barred. (B-subscriber has installed restrictions against incoming link, or the requested service, not supported by the B-subscriber)
62 | Call rejected. (To A-subscriber: Link request actively rejected by B-subscriber, by sending a DISC in response to an incoming SETUP. To a TE during the phase in which an incoming call is being established: The call has already been accepted by another TE on the bus.)
89 | Network congestion. (Bottleneck situation in the network; for example, all-trunks-busy, no conference set free.)
90 | Remote user initiated. (Rejected or cleared down by remote user or exchange.)
112 | Local procedure error. (In REL: Call cleared down as a result of local errors, for example, invalid messages or parameters, expiry of timeout. In SUS REJ: The link must not be suspended because another facility is already active. In RES REJ: No suspended call available. In FAC REJ: No further facility can be requested because one facility is already being processed, or the specified facility cannot be requested in the present call status.)
113 | Remote procedure error. (Call cleared down because of error at remote end.)
114 | Remote user suspended. (The call has been placed on hold or suspended, at the remote end.)
115 | Remote user resumed. (Call at remote end is no longer on hold, suspended, or in the conference status.)
127 | User Info discarded locally. (The USER INFO message is rejected locally. This cause is specified in the CON message.)

Table A-2 lists the cause codes for the 1TR6 switch type.

## Common problems and their solutions

This section lists problems you might encounter and describes ways to resolve them. It categorizes common problems as general problems, configuration problems, hardware configuration problems, ISDN interface problems, and problems indicated by the LEDs.

### General problems

#### DO menus do not allow most operations

When the list of DO commands appears, many operations might not be not available if the right profile has not been selected. Because the MAX can manage a number of calls simultaneously, you might need to select a specific Connection profile, Port profile, or Call profile in order to see certain DO commands. For example, to dial from a Call profile or a Connection profile, you must move to the Call profile (Host/6 > Port N Menu > Directory) or the Connection profile and press Ctrl-D 1.

Note that you cannot dial if Operations=No for the control port. If a call is already active, DO 2 (Hang Up) appears instead of DO 1 (Dial). If the T1 or E1 line is not available, Trunk Down appears in the message log and you cannot dial.

#### POST takes more than 30 seconds to complete

In earlier versions of the software, the MAX downloaded the required code and immediately commenced with AT POST (which sends the string `AT` to each modem and waits for the modem to respond with "OK"). With the current software, the MAX downloads the modem code, waits for the modems to checksum the downloaded code, and then verifies that the checksum matches before continuing. If the checksum does not match, the MAX downloads the code again, up to two more times. If the checksum still does not match after three download attempts, the MAX fails the entire slot card.

This feature helps to reduce the POST failure rates for the 12MOD cards.The 12MOD digital modem slot card boots every time the MAX power-cycles, and requires boot-up configuration data from the MAX. If the first boot-up fails, the MAX makes two further attempts to download the code for the MAX unit's 12MOD digital 12-modem slot card.

### Configuration problems

The most common problems result from improperly configured profiles.

#### Some channels do not connect

You might encounter a problem in which the Line Status menu shows that the MAX is calling multiple channels simultaneously, but only some of the channels connect. In this case, an international MAX placed the call, or the call was from the U.S. to another country. In some countries, setting the Parallel Dial parameter in the System profile to a value higher than 1 or 2 violates certain dialing rules, and only some of the channels can connect during call setup. Try reducing the Parallel Dial parameter value to 2. If the problem persists, try reducing it to 1.

#### Data is corrupted on some international calls

You might notice that the data appears to be corrupted on single- or multichannel calls dialed from the U.S. to another country. On some international calls, the data service per channel is not conveyed by the WAN to the MAX answering the call. You must therefore set Force 56=Yes in the Call profile. If you do not, the MAX incorrectly thinks that the call uses 64-Kbps channels.

#### Only the base channel connects

You might encounter a problem in which the first channel of an inverse multiplexing or MP+ call connects, but the call then clears or does not connect on the remaining channels.

The most common error in defining Line N profiles is specifying incorrect phone numbers. The MAX cannot successfully build inverse multiplexing or MP+ calls if the phone numbers in the Line N profile of the called unit are incorrect. The phone numbers that you specify in the Line N profile are the numbers local to your unit. Do not enter the phone numbers of the MAX you are calling. Enter those numbers in the Call profile, Destination profile, or Connection profile.

In addition, when you are using E1 or T1 lines, any phone numbers you specify must correspond to those channels within the circuit that are available for data transmission. For example, if channels 13-21 are allocated to a particular slot, you must specify the phone numbers for channels 13-21 in the Line N profile. Switched data channels do not have to be contiguous within the circuit.

#### No Channel Avail error message

If the error message No Channel Avail appears in the message log display when the MAX tries to place a call, check the Line N profile configuration. This message can also indicate that the lines' cables have been disconnected or were installed incorrectly.

#### Restored configuration has incorrect RADIUS parameters

On earlier RADIUS Servers, the submenu consisted of three clients (specific host addresses) and one Server Key for all three clients. If the MAX supports the new RADIUS Server, the restoration of the MAX configuration will cause a problem, because the new RADIUS Server allows up to nine addresses (host or net) and a Server Key for each address. When you restore configurations with the old Client Address list, the subnet mask assigned to the clients will be the default subnet mask of the address type given (for example, 128.50.1.1 will get a subnet mask of 16) and not the previous 32-bit (single host) address. In addition, the Server Key will not automatically be set. You must set the Server Key manually for each client in the RADIUS Server submenu.

### Hardware configuration problems

If you cannot communicate with the MAX through the VT100 control terminal, you might have a problem with terminal configuration, the control port cable, or the MAX hardware.

#### Cannot access the VT100 interface

If no data is displayed on the VT100 interface, verify that the unit completes all of the Power-On Self Tests. Proceed as follows:

1. Verify that the MAX and your terminal are set at the same speed.

2. Locate the LED labeled Fault.

3. Switch on the MAX.

The Fault LED should remain off except during the Power-On Self Tests. If you are using the VT100 interface, press Ctrl-L to refresh the screen.

If the Fault LED remains on longer than a minute, there is a MAX hardware failure. A blinking Fault LED also indicates a hardware failure. Should these situations arise, contact Ascend Customer Service.

#### Fault LED is off but no menus are displayed

If the unit passed its Power-On Self Tests and you still cannot communicate with the VT100 interface, type Ctrl-L to refresh the screen. If you still do not see any data, check the cabling between the MAX and your terminal as follows:

1. Check the pin-out carefully on the 9-pin cable.

The control terminal plugs into the HHT-VT100 cable or the 9-pin connector labeled Control on the back of the MAX. If you are connecting to an IBM PC-like 9-pin serial connector, a straight-through cable is appropriate. Otherwise, you might need a 9-to-25 pin conversion cable.

2. Check the flow control settings on your VT100 terminal.

   If you are not communicating at all with the MAX, see whether you can establish communication after you have turned off all transmit and receive flow control at your terminal or terminal emulator.

3. Determine whether you need a null-modem cable converter.

   Though generally not needed, occasionally a null-modem cable converter is required for a few of the large numbers of different cable and terminal configurations that are available.

#### Random characters appear in the VT100 interface

If random or illegible characters appear on your display, you probably have a communications settings problem. Specify the following settings:

- 9600 bps data rate

- 8 data bits

- 1 stop bit

- No flow control

- No parity

If you have changed the data rate through the Port profile, make certain that your VT100 terminal matches that rate.

#### A Power-On Self Test fails

If the start-up display indicates a failure in any part of the POST, an internal hardware failure has occurred with the unit. In this case, contact Ascend Customer Service.

### ISDN BRI interface problems

Problems sometimes encountered with ISDN BRI interfaces include calls not dialed or answered reliably, BRI lines not dialing or answering calls, apparent logical-link failures, and WAN calling errors in netbound BRI calls.

#### Calls are not dialed or answered reliably

If calls are not dialed or answered reliably, check your cabling.

The first and most critical aspect of the interface is the physical cable connecting the MAX to the line or terminating equipment. Typically, WAN interface cabling problems appear immediately after installation. If you are unsure about the cabling required, contact Ascend Customer Service. The Hardware Installation Guide for your MAX describes the general PRI and BRI interface requirements and lists cabling pin-outs.

#### No Logical Link status

If you notice that the status of a Net/BRI line in the Line Status display is No Logical Link, you might or might not have a problem.

In some countries outside the U.S., it is common for no logical link to exist before the MAX places a call. In the U.S., when you first plug a line into the MAX or switch power on, the central office switch can take as long as 15 minutes to recognize that the line is now available. You might have to wait that long for the line state to change to Active (A). The physical link can exist without a logical link up on the line.

If you wait longer than 15 minutes and the line is still not available:

1. Determine whether all the ISDN telephone cables are wired straight through.

If you are running multipoint (passive bus) on your switch, all of the ISDN telephone cables must be wired straight through. If any of the cables are wired to cross over, you will not be able to place calls.

2. Verify that 100% termination is provided on each ISDN line.

3. Determine whether you have correctly specified the Service Profile Identifiers (SPIDs) in the Line N profile for each line. If the SPIDs are not correctly specified, the line status might indicate No Logical Link. Check with your system manager or carrier representative to obtain the SPID or SPIDs for your line. To specify your SPIDs, use the Pri SPID and Sec SPID parameters in the Line N profile.

#### WAN calling errors occur in outbound BRI calls

Should you encounter a problem in which the Call Status window immediately indicates a WAN calling error when the MAX places a call on a Net/BRI module. Proceed as follows:

1. Check the value of the Data Svc parameter in the Call or Connection profile.

Try both the 64K and 56K options for Data Svc, to see whether using a different value solves the problem.

2. Verify that you are using the correct dialing plan.

   Depending on how the BRI lines are configured, you might need to type four, seven, or ten digits to communicate with the remote end.

   Four-digit dialing involves the last four digits of your phone number. For example, if your phone number is (415) 555-9015, four-digit dialing requires that you enter only the last four digits: 9015. Seven-digit dialing specifies that you dial the digits 5559015, and ten-digit dialing requires 4155559015.

   If you are sending the incorrect number of digits, the MAX cannot route the call. Ask your carrier representative for the correct dialing plan, or simply try all of the possibilities.

3. Ask your carrier representative to verify explicitly that the line is capable of supporting the call types you are requesting.

### Bridge/router problems

Problems with a bridge or router can include the uncertainty of link quality and the MAX hanging up after answering an IP call.

#### The link is of uncertain quality

When running File Transfer Protocol (FTP), the data transfer rate appears in bytes per second. Multiply this rate times 8 to get the bits per second. For example, suppose that you are connected to Detroit on a 56-Kbps B channel and that FTP indicates a 5.8 Kbyte/s data rate. In this case, the link is running at 5.8x8=46.8 Kbps, or approximately 83% efficiency. Many factors can affect efficiency, including the load on the FTP server, the round-trip delay, the overall traffic between endpoints, and the link quality.

You can check link quality in the WAN Stat status window, or by running a Ping between the same endpoints. Dropped packets hurt the link's efficiency, as does round-trip delay. Random round-trip delay indicates heavy traffic, a condition that also drops the efficiency of the link.

#### The MAX hangs up after answering an IP call

If the MAX hangs up after answering an IP call, proceed as follows:

1. If you are running PPP, verify that you have entered the proper passwords.

2. Verify that Auth is set to PAP or CHAP.

3. If you are routing IP over PPP, verify that the calling device gives its IP address

   Some calling devices supply their names, but not their IP addresses. However, you can derive an IP address if the calling device is listed in a local Connection profile or on a RADIUS authentication server. Try enabling PAP or CHAP for the Recv Auth parameter so that the MAX matches the caller's name to the Station parameter in a Connection profile and gets the corresponding LAN Adrs.

Copyright © 1998, Ascend Communications, Inc. All rights reserved.