Troubleshooting the VoIP call quality issues

Troubleshooting the VoIP call quality issues

We have all been frustrated at poor voice call quality on phone services.  It can be noise or chopping on the line or sounding like you have breathed helium.  VoIP is no different.   The typical business will refer problems to the business VoIP phone service supplier providing the VoIP support contract. It causes further frustration and delays if the fault is not with the VoIP for business system and the business needs to make a second support call to another service provider.

In the event of failure or call poor quality there are a few steps that the business can take prior to making the call to make sure that the problem does not arise elsewhere and the support call can be correctly placed.

Poor call quality can arise in at least three areas: the business network itself; the VoIP system – centrally and at the desktop VoIP phone for business; and the Internet or PSTN service provider.

The first step is to identify who has the problem:

  1. All users indicate a central network, VoIP system or external connectivity problem.
  2. Groups of Users indicates a network or central VoIP issue;
  3. An individual user indicates a network connectivity problem, a handset configuration problem, or a need for user training.

All Users

  1. Check that all central networking and VoIP hardware is operating correctly. Component failure in either may allow services to continue but in a degraded manner.   For instance, cooling fan failure causing overheating can cause strange operational effects.
  2. Check connectivity between the VoIP system and the corporate network. Not all network hardware faults are obvious.
  3. If internal calls are ok, but some or all outside calls are not, it could be that external Internet or PSTN problems are causing poor call quality.
  4. Have any changes been made to the central network configuration? Call Quality depends on the network being correctly configured according to the VoIP phone service  Addition of new or replacement equipment or reconfiguration, in general, may have invalidated these criteria.
  5. Have any changes been made to the VoIP installation, including software upgrades? Upgrades may have overridden site-specific configuration information. VoIP for business, particularly if it is to be used with video-conferencing needs specific configuration settings.

Groups of Users

Groups of users can be physically related in that they use a common connection to the corporate network, or logically connected, for example, having a common user profile or group membership.

  1. If the group of users is physically related, then there may be a problem with the equipment where the users collectively join the network. This is usually a network switch which may be faulty or misconfigured.  Check also the upstream switch to make sure that the upstream point of entry is correctly configured.
  2. If the group of users is logically connected, check to see if the common basic profile or group information has been changed, possibly following a central software upgrade, or as a by-product of another change.

Individual Users

Resolving individual user problems can be a little more tricky and involve elements of central and group investigations, investigation of the user’s handset, and even of the user’s level of proficiency with the VoIP system.

  1. There may be an issue with the physical connection to the corporate network: at the handset; at the wall point: or at the network switch.   This is where call quality problems usually arise.Wall points and cables are often damaged in the normal office environment.  It’s obvious if a wall point has been yanked out of the wall, but they can also have faults that are not immediately obvious, particularly if a cable is internally damaged but not broken.  Poor quality or damaged cables and connections will degrade the quality of voice and data transmitted over the network. Check for local building activity causing inadvertent damage to cabling.VoIP phones usually have two network connectors, one to connect the phone to the corporate network, and a pass through connector from the handset to a computer.  Check that these are connected the correct way around.

    The port on the network switch to which the handset is attached could be misconfigured.

  1. The handset may be damaged or misconfigured.Check the physical integrity of the handset.  A faulty microphone or speaker will affect call quality.Basic configuration is downloaded to the handset when it is connected, but some local configuration is possible.  If there has been a central software upgrade the handset configuration may have altered.

    Check for users attempting to do their own thing with the handset programming, particularly trying to get around call restrictions or programme speed dial buttons.


  1. A Non-VoIP hardware or software issue – call the appropriate internal or external support service.
  2. A VoIP hardware or software issue – call your business VoIP phone service for support.


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