Disable SIP ALG on SonicWall

Step-by-step guide

Complete the following steps to properly configure your SonicWall device.  Note: These images may differ from the current version of software.

1. Log into the device’s web configuration utility
2. Select VoIP, Settings
3. Check Enable consistent NAT
4. Uncheck all other Settings
   
5. Click Accept

Also will need to change the UDP timeout Under Firewall > Advanced
- Set UDP Connection Timeout to 120 seconds

Once you change the setting to 120 seconds go under Firewall --> Access Rules

Select your Lan --> Wan and click Edit

Under Advanced Tab 

• UDP Connection Inactivity Timeout (seconds): 30

Change to:

• UDP Connection Inactivity Timeout (seconds): 120

Do the same for Wan --> to Lan