D-Link DWR-730 User Manual page 31

Section 3 - Configuration
ALg
Application Level Gateways (ALG) allow certain applications
to augment a network's firewall or NAT. This section
enables you to enable various ALGs as required by specific
applications. To enable an ALG, check the box next to the
name of the rule.
SIP Port:
Enter the Session Initiation Protocol (SIP) port required by
your applications.
Click Apply to save the settings and return to the Network
page.
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