SonicWall firewall VoIP configuration

SonicWall firewall VoIP configuration

The default firewall settings on SonicWall firewalls may cause issues with VentureTel VoIP traffic.  Some issues you may see are:
  1. Problems with phone registrations
  2. Dropped calls
  3. Phones not ringing
  4. One-way audio
The TZ400 is an exception to this requirement. For the TZ400 model, Consistent NAT should be enabled.

Disable Consistent NAT and SIP Transformations

  1. Go to VoIP > Settings.
  2. Uncheck the boxes next to Enable Consistent NAT and Enable SIP Transformations.


Disable Stealth Mode and RTSP

  1. Go to Firewall Settings > Advanced.
  2. Uncheck the boxes next to Enable Stealth Mode and Enable RTSP Transformations.

Additional Information

Known Issues

  • SonicWall TZ400/TZ500 requires Consistent NAT to be on. The exception to this would be if the TZ400 is on firmware version SonicOS Enhanced 6.2.5.3-35n. With this firmware version, disable Consistent NAT.
  • Firmware version 6.2.3.x causes Duplicate UDP ports regardless of NAT settings.
  • Firmware version 6.2.7 has DPI (deep packet inspection) under access groups on NSA series, which causes Call Quality issues despite rules added in.
  • Firmware version 6.2.7.x (and higher): 802.1p tagging breaks phone connectivity.
  • Additional testing has found that the "Consistent NAT" setting may need to be toggled depending on the firmware version in use. It may be necessary to toggle this setting on or off depending on the issues being experienced and then testing for stability. 
  • The following SonicWall models and firmware versions require Consistent NAT turned ON: SonicOS NSA 2600 Enhanced 6.2.2.1-14n(device needs to be restarted in order for the setting to stick)
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