SIP transformations can alter signaling. When investigating registration, audio or dropped-call problems, compare a controlled call before and after the relevant setting change.
SonicOS 7.x
- Record the current configuration and arrange a quiet maintenance window. Network changes may interrupt calls.
- Open Network → VoIP → Settings and locate Enable SIP Transformations.
- If the investigation calls for disabling SIP ALG, clear that setting and apply. Do not clear every VoIP or security option.
- Consider Consistent NAT only where needed for the deployment; it changes address/port predictability and is a separate choice.
- Retest registration, inbound/outbound calls and two-way audio, including after an idle period. Restore the previous configuration if the change does not help.
Menu locations vary by SonicOS release. Follow SonicWall’s SIP ALG instructions for your version. A successful registration alone does not verify media or long-call stability.