IP Office Troubleshooting
VoIP Calls Echo or Have Poor Speech Quality
Calls over VoIP trunks echo or have poor speech quality.
I. Check that when the problem is experienced that the call is not terminating on an analog Central Office/Network Provider endpoint. If there is an analog endpoint at the end of an IP connection, delays or echoes are likely and no action is necessary.
To verify if the external call is terminating on an analog endpoint, address the following questions to the user experiencing the problem:
1. Was the external call made to a home number or a home office?
• If the answer is YES, it most likely means the call terminates on an analog endpoint.
• If the answer is NO, ask question 2.
2. If the external call was made to an office, how many employees are in the company?
• If the number is small, it most likely means the call terminates on an analog endpoint.
• If the number is large, it may mean that the endpoint is not analog, so continue with the rest of the troubleshooting actions.
Actions within a Small Community Network (SCN)
If you have determined that the call terminates on an IP endpoint (for example, the problem is experienced during calls between remote IP Office sites/within a Small Community Network), perform the following actions.
II. Verify the following configuration settings on the IP trunk:
To look at the settings within Manager:
1. Log onto Manager and open the IP Office configuration.
2. From the Configuration Tree, click Line and double-click the IP trunk in question.
3. Within the VoIP tab:
i. Confirm that the Codec selections are consistent between the IP-based systems.
• Compression Mode: Needs to be hard coded (have a selection OTHER THAN Automatic) and the setting must be the same at both the IP Office sites. This is necessary to make use of the most suitable bandwidth available.
• H450 Support: This field selects the supplementary service signaling method for use across H.323 connections. The selected method must be supported by the remote end. For IP Office to IP Office connections, H450 is preferred.
ii. Confirm the following settings at all the IP-based systems:
• Enable Faststart: Needs to be UN-CHECKED (DISABLED). Having Faststart enabled can effect line quality because certainverifications/handshakes are skipped.
• Allow Direct Media Path: Needs to be CHECKED (ENABLED). Enabling Direct Media Path allows the system to make use of the most direct connection between the two IP endpoints. Providing both systems support it.
• Out-Of-Band DTMF: Needs to be ENABLED.
• Voice Networking: Needs to be ENABLED. This will enable Small Community Networking.
4. Click OK.
5. If any updates have been made and needs to be saved, click and accept the selected reboot mode by clicking OK.
III. Check that the VoIP lines between networked sites are set up via a star configuration and NOT multi mesh. Depending if SCN is enabled or disabled.
Correct only when SCN is enabled Correct only if SCN is disabled
A star configuration generates less SCN traffic on the IP trunks. Hence, it is the preferred configuration to help increase speech quality
To see which VoIP line configuration exists on the network, look at the number of IP trunks configured on each IP Office system.
1. Log onto Manager and open a remote site's IP Office configuration.
2. From the Configuration Tree, click Line. How many configured IP trunks do you see?
3. Now open the central site's IP Office configuration and open the Line configuration, how many IP trunks do you see?
4. From this information, you can work out how the VoIP lines are configured.
IV. Check with the Central Office/Network Provider that the Committed Information Rate (CIR) on Frame Relay is set for an acceptable level, as per the frame size. The setting should never be zero.
V. Verify the following with the System Administrator or the local IT Administrator:
1. Check that VLAN is enabled on all links to separate Voice and Data where available.
2. Check that Diffserve is enabled on supported routers and systems. Also check that the Diffserv Code Point (DSCP) is consistent throughout.
3. Check to see how voice calls are being routed. To do this you can use the Call Status application.
• Frame Relay
• ADSL link
VI. If the problem persists after you have performed ALL these troubleshooting steps, gather the following information BEFORE escalating the issue:
• A copy of the IP Office configuration will be useful before escalating to your support organization.
• The username and password of the configuration must be provided to your support organization for testing purposes.
• Any trace codes or log files generated by the System Monitor application (if available).
• Notes relating to the result of each of the verification steps performed above.
• The customer's network diagram (if applicable).
Retry the voice call to verify that the speech quality is better.