SIP Trunk with Dyn DNS Not Reconnecting Automatically After modem Reboot or IP Change

[vietridaniele]

Hello,
I’m experiencing an issue with my SIP Trunk configured on 3CX, where the Registrar/Server uses a dynamic DNS (DynDNS). The dynamic DNS itself works perfectly and consistently resolves to the correct public IP address of my Fritzbox. Initially, the SIP trunk connects successfully without issues.

However, when the Fritzbox is rebooted, or its public IP changes for any reason, the SIP trunk in 3CX does not reconnect automatically. Even though the DynDNS has updated to the new IP, the SIP trunk remains in a "red" (disconnected) state. The only way to restore the connection is to manually click on the three dots next to the SIP trunk in the 3CX interface and select "Refresh Registration."

This issue persists despite the correct configuration of the DynDNS and proper functionality of the Fritzbox. It seems 3CX is not automatically refreshing the registration or resolving the updated IP from the dynamic DNS after an IP change or Fritzbox reboot.

I would appreciate any insights or recommendations to resolve this issue, such as ensuring automatic re-registration or enabling proper handling of dynamic IP changes in 3CX.

 

[NicholasP_3CX]

You dont really need to use DynDNS. Just define the PBX with a Dynamic IP address and when the IP address of the internet connection changes, it will update the 3CX DNS record.

Do you have an on prem system, because I can see that you have a 3CX SMB Free instance.

 

[vietridaniele]

thanks for the reply. no, i m using only the free instance for now and the problem is on this one. the hosted one i let it expire because i was having many isseus since last update. i m testing now with the free one and if everything goes well i will re-subscribe.

i suppose your solution is only for the on premise system?
thanks again

 

[NicholasP_3CX]

Yes, as all the free editions have a static IP Address.

 

[Anion]

Check the trunk settings for the time you have to update SIP records.