The Router Settings Relevant with One Way Audio & 30 Seconds Call Hang up Issue

Users might meet the SIP Call issue including:

  • One way audio
  • No audio in both way
  • Call hangs up at 30 seconds

Mostly it is relevant to the router, firewall, or VPN gateway settings. We often suggest client disable SIP ALG, SIP forwarding or something like that.

Specifically the one-way audio or no audio issue. It's also could be caused by the incorrect port forwarding settings on the router.

In this article, we would offer some settings that we had experienced. But each router manufacture might have their own naming rules or logic principle for the settings. So we could not cover all.


We only offer a suggestion for the router settings. But we don't offer support to debug your router. If you need the support of the router settings or you don't have the knowledge of router settings, please seek help from the rouer support or your IT guy.

The reference includes 2 parts.

  • ALG Settings References
  • RTP Port Forwarding References


ALG Settings References

1. Disable SIP ALG on Cisco Router with CLI only.

Command: no ip nat service sip udp port 5060


2. Disable SIP ALG option in Cisco RV320 router.


3. Disable SIP ALG on Huawei HG8145V


4.  Enable consistent NAT on SonicWall, and Disable SIP Transformations.



5. Disable SIP ALG on Billion router.


6. Disable SIP Passthrought on Asus RT-N66U router.


7. Disable SIP ALG, and check Non-NAT option on TP-Link TL-ER6020.


8. Disable SIP ALG on D-Link DIR-605L

9. Disable SIP ALG on RouterOS-MikroTik

IP-->Firewall--> Service Ports


10. Disable SIP ALG on Draytek Firewall


If you have a sample of other brand router settings about ALG that not mentioned here, you might comment at the bottom of this article. It would be appreciated!

RTP Port Forwarding References

Jump to this article: Port Forwarding Settings on the Router References



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  • 0

    Well in our case it's vice versa, as when we DO add command

    no ip nat service sip udp port 5060

    in our Cisco router, incoming calls are being dropped after 30 seconds..

  • 0

    Hi Hm,

    This is article is not a 100% correct solution and just for reference.

    Yes, in practical case it is possible to be your situation. It's odd. But just choose the proper solution.

    Good luck!

  • 0

    Hey Hey Mr Hm, 


    we're having same issue with out SIP Trunk from ITSP, the incoming calls are dropping exactly after 30 seconds... And this is driving me nuts. 


  • 0

    Bonjour ,

    J'ai exactement le même problème  c'est à dire les appels(entre deux soft-phones) tombent au bout de 31 secondes mais je suis sur un pfsense .


    Merci de m'aider si vous avez une solution 

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