An Engineers Notebook

How to disable SIP ALG on a Draytek router

etworks with VOIP might require SIP ALG (Session Initiation Protocol (SIP) Application Layer Gateway (ALG)) disabling on a Draytek router to prevent disruption VOIP functionality.

1) Logon to the Draytek via it’s web interface, under ‘Management’ ensure that ‘Telnet’ is enabled.
2) Use Telnet via the Windows Command Prompt. (if Telnet Client is not installed you can follow this guide)
3) Issue the following commands:
sys sip_alg ?

Check to see if SIP ALG is disabled or Enabled
Checks if SIP ALG is enabled or not, if it is:
sys sip_alg 0
sys commit
sys reboot

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