Symptom The common symptoms of narrowband fax service failures are as follows: - The sending or receiving of fax fails, which results in the high fax failure rate.
- The received fax is incomplete, for example, fax page missing or line missing.
Possible Causes Table 1 Mapping between fault symptoms and possible causes | Symptom | Possible Cause | | The sending or receiving of fax fails. | - Misoperation exists.
- The fax machine is faulty.
- The data configuration is incorrect.
- The QoS of the bearer network is poor.
- Problems lie in the signaling messages.
| | The received fax is incomplete. | - The QoS of the bearer network is poor.
- Problems lie in the signaling messages.
| Fault Diagnosis Figure 1 shows the procedure for troubleshooting the narrowband fax service failure. Figure 1 Procedure for troubleshooting the narrowband fax service failure
http://localhost:7890/pages/31184407/11/31184407/11/resources/figure/fig_cn_43_25_0003501.png Procedure Check the Misoperation - Check whether the sending or receiving of fax fails.
- The sending of fax fails. => 2
- The receiving of fax fails. => 4
- Check whether the information "The fax paper is ready" is displayed on the fax machine before sending a fax.
- Yes => 7
- No => Place the paper in the fax machine properly and then send the fax again.
- Check whether the start key is pressed after the peer fax machine sends the fax tone.
- Yes => 7
- No => Press the start key after hearing the fax tone sent from peer fax machine.
- Check whether the fax machine has enough papers.
- Yes => 5
- No => Put more papers in the fax machine.
- Check whether the ink box is used up.
- Yes => Change the ink box.
- No => 6
- Check whether the memory of the fax machine has free space.
- No => Contact the supplier of the fax machine to repair the fax machine.
- Yes => 7
Check the Fax Machine - Connect the fax machine to the PSTN and send a fax. Check whether the fax can be sent successfully.
- No => Contact the supplier of the fax machine to repair the fax machine.
- Yes => 8
Check the Data Configuration - Check whether the data for the MGW to support the fax and modem functions is configured on the SoftX3000.
Run LST MGW to check whether Special attributes in the command output is No fax or No modem. - Yes => Run MOD MGW to configure data on the SoftX3000 to enable the MGW to support the fax and modem functions.
- No => 9
- Check whether the data for the MGW to support the V3 fax flow is configured on the SoftX3000.
Run LST MGW to check whether Special attributes in the command output is V3 fax flow. - Yes => 10
- No => Run MOD MGW to configure data on the SoftX3000 to enable the MGW to support the V3 fax flow.
- Check whether the codec configured for the MGW on the SoftX3000 is correct based on the fax type.
Run LST MGW. If Fax type is Transparent transmission, check whether Codec list in the command output is G.711A or G.711u; ifFax type is T38, check whether Codec list in the command output is T.38. - Yes => 11
- No => Run MOD MGW to modify the configuration.
- Ensure that the data for the MGW to support the echo cancellation function is configured on the SoftX3000.
Run LST MGW to check whether the MGW is configured to support the echo cancellation function. Check the Signaling Message - On the LMT of the SoftX3000, the messages of the MGWs involved in the fax service are traced. Check whether the fax event is reported properly and whether the SoftX3000 sends the message to instruct the MGW to switch over to the fax service.
- Yes => 13
- No => Contact Huawei technical support engineers.
- H.248 message
- If the H.248 message is in text format, "V21flag" contained in the NTFY_REQ message reported by the MGW indicates a fax event.
MediagatewayID: [191.1.80.1]:2944 T=468662211{C=10{N=A54{OE=369101343{20050420T12141900:ctyp/dtone{dtt=V21flag}}}}} - If the H.248 message is in binary mode, "ctyp dtone" contained in the NTFY_REQ message reported by the MGW indicates a fax event, as shown in Figure 2.
Figure 2 Fax event indicated by the H.248 message in binary mode
http://localhost:7890/pages/31184407/11/31184407/11/resources/figure/fig_cn_43_25_0003502.png
- After receiving the NTFY_REQ message, the MGC sends a MOD_REQ message to instruct the MGW to switch over to the fax service.
- MGCP message
Check the QoS of the Bearer Network - Ping the media gateway device on the LAN Switch and check whether the QoS of the bearer network is poor based on the analysis provided in Table 2 and Table 3.
http://localhost:7890/pages/31184407/11/31184407/11/resources/public_sys-resources/icon-note.gif NOTE: If the fax service requires the cooperation of the bearer network, and the MGW is the UMG8900, you can run LOP E1 on the UMG8900 to perform loopback test to check whether errors occur on the bearer network.
- If the QoS of the bearer network is poor, contact Huawei technical support engineers and select the T.38 fax that requires less bandwidth.
Check the Clock Phase Lock - Check whether the clock phase lock of the trunk gateway is normal and any alarm is generated for the E1 channel.
- Yes => Check the configuration on the MGW.
- No => Contact Huawei technical support engineers.
- The following commands are used to query the clock on the TMG:
- (Maintenance mode)show pll-state <SMB Slot number>
- (Maintenance mode)show board-clk <VSP/VSU Slot number>
- The following commands are used to query the E1 channel on the TMG:
- (Maintenance mode)show pcm-port
- (Maintenance mode)show pcm-state
- The following commands are used to query the clock on the UMG8900:
-
The following commands are used to query the E1 channel on the UMG8900:
Related Information When the Ping command is executed, if the packet loss rate reaches or exceeds 1%, the fax service in the transparent transmission mode is affected, as shown in Table 2. Table 2 Analysis of QoS of the bearer network based on the output of the Ping command | Item | QoS | Unidirectional Delay (ms) | Packet Loss Rate | Jitter (ms) | | 1 | Good (recommended) | ≤40 | ≤0.1% | ≤10 | | 2 | Poor | ≤100 | ≤1% | ≤20 | | 3 | Bad | ≤400 | ≤5% | ≤60 | Table 3 lists the implementation of the fax service on the network with different QoS. Table 3 Implementation of the fax service on the network with different QoS | Service Type | Network with Good QoS | Network with Poor QoS | Network with Bad QoS | | Modem | Transparent transmission | Available | Unavailable | | Fax | Transparent transmission | Available | Unavailable | | T.38 | Available | Available | |
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