Knowledgebase
What issues can SIP ALGs cause? Why you should disable them on your router.
Posted by Michael S. on 27 July 2021 11:57 AM

What are SIP ALGs?

SIP ALG stands for Session Initiation Protocol Application Layer Gateway.  Most routers and modem-router gateways have these enabled by default. SIP ALGs interfere with SIP packets, modifies them, and send them to your provider. In our case, to Vantact. In reality, our hosted platform does not require these modifications, and more often than not, SIP ALGs break the SIP information and cause trouble.

 

What kind of issues can SIP ALGs cause?

  • When one party cannot hear the other.
  • Phones losing registration and going offline until a timeout happens.
  • Not being able to transfer calls.
  • Not being able to retrieve parked calls.
  • Some phones within a ring group do not ring.
  • Inbound calls do not ring
  • Dead air or dropped calls when picking up incoming calls
  • Other random issues

 

What should you do if you have SIP ALGs issues?

You should disable any SIP ALGs or SIP Transformation features on your router. Visit our article: How to disable SIP ALGs on most brands of routers and modems.