Home > Problems > Hum

Problem: Hum

Hum is generally due to the introduction of AC power supply noise into the non-packet parts of the voice path. Typical causes are wiring running too close to power transformers or power lines, leaky power supplies (typically "wall bricks") and common mode noise due to poor grounding.

Impact

Users report a noticeable low frequency hum.

Resolution

Try to correlate the incidence of noise with specific routes or pieces of equipment (including telephone handsets). Possible causes include the power supply to the handset, if an IP phone, or the routing of loop wiring if an analog handset.

If the problem appears to be associated with a specific route that connects to an analog or TDM trunk then check the Gateway for possible problems.

Back To Top

Conditions of use: The material on this site is copyright VoIP Troubleshooter LLC and may be freely used but not copied or downloaded.  In making use of this site the user acknowledges that VoIP Troubleshooter LLC or Contributor has no liability for any issues or problems that may arise directly or indirectly as a result of such use.  VoIP Troubleshooter LLC and Contributor are providing this material as-is with no warranty as to correctness or completeness and do not accept any responsibility for any issues or problems of any nature whatsoever that may arise from the use of the material on this site.