3cx sip trunk issues with Draytek routers

[russellcrowe]

Hi

i am having issues getting SIP trunks to work behind Draytek routers

i have been using voip-unlimted and Spitfire sip trunks
3cx version 9 sp5

i had an old draytek 2800 router and this work ok

but have replaced with a draytek 2820 and can not get sip trunks to register or remote snom phones to work
using port forwarding

do not think a 3cx congfig issue because if i swap router back then all works

tried several versions of firmware on the 2820 but makes no difference

i have also had this problem with a customer which is why i am testing with new draytek 2820

has anyone had these problems with draytek routers

thanks
Russell

ps can any one recommed a good router that works with 3CX prefer a 2 WAN port router

 

[complex1]

Hi Russell,

A DrayTek router should work fine, because I am using different DrayTek’s on different locations. Such as the vigor 2200E+, 2800, 2800V, 2910, 2930n and 2930VS
There is a 3CX server behind the vigor 2800 and 2930n, behind the other routers are only phones located.

The routers with build-in VoIP, I disabled the VoIP and changed the SIP port 5060 to another port number, because sometimes DrayTek will mess-up SIP traffic.

Q. After you have switched the router by a other one, did you restart the 3CX server?

 

[russellcrowe]

yes did restart the 3cx server

when i do the firewall test on 3cx it passes with warnings saying some functionality migh not work
but it passes ok on the draytek 2800

something on the 2820

i have tried a 2910 and had problems with voip-unlimited sip trunks

thanks
Russell

 

[complex1]

Please reset the router to factory default, then setup NAT >> Open Ports >> Index 1
Fill the fields with TCP/UDP 5060, TCP/UDP 5090 and UDP 9000~9049
Then rerun the firewall test. When it results with any warning then you have to solve this first before continuing.
If the tests result without warnings then you may setup the complete router. Don’t forget to enable DoS Defense, this is prio 1.

Q. The vigors you using are without build-in VoIP?

 

[RichardCrabb1]

Registering SIP Trunks
I did see a problem whereby the 2820 DNS proxy was not working correctly. This stopped SIP registration with Voip Unlimited. The way around it is to set the DNS on the 3CX machine to that provided by the ISP, rather than pointing it to the router.


Incoming Calls
There is an issue with Voip Unlimited for incoming calls via Draytek 2820 routers. The way around it is to use 3.3.3_232201 firmware. This is caused by a large IP SIP packet that is fragmented, but the router will not forward it. I understand that the new version will work if the checkbox under firewall -> general setup -> Accept large incoming fragmented UDP or ICMP packets is UNTICKED. This is the opposite to what you would expect.

Kind regards
Richard Crabb