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Full Version: STUN setting with DNS-SRV transport is not working
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I configured STUN NAT traversal and configured as my stun server with DNS-SRV as transport on all T-38P, T-28P, T-22P phones.

None of these phones seem to send CLASSIC-STUN request out when DNS-SRV setting is on. Irrespective of the phone type/firmware this problem persists.

With UDP transport, STUN request is out from the phone.
Find the zip attachment with phone configuration and pcap traces with both dns-srv setting and udp setting.

Sorry for our delay.
I have submitted your issue and trace to our engineer, if any other information needed i will let you know ASAP.
For this issue, the reason is your DNS server didn't configure the NAPTR and SRV record in outbound domain name.
When transport type is DNS-SRV, the phone can't search the result, so can't select the correct transport type, and didn't send CLASSIC-STUN request.
So if you want to use DNS-SRV, you need to configure the NAPTR and SRV record in your outbound domain name.
If you didn't configure the NAPTR and SRV record in outbound domain name, you can use UDP transport type.

I'm a bit late replying, but perhaps this will help.

I am the maintainer of the domain including the STUN server at I do keep a DNS-SRV record for _stun on the domain for both UDP and TCP.

I strongly suspect that the solution to the above problem is that you just need to specify "" as the server if you want to use DNS-SRV as the DNS resolution technique.

Hope this helps,
Thanks for your reply.
Our engineer said we will evaluate this problem in our next commercial firmware.
BTW, you should configure NAPTR and SRV record of outbound domain in your DNS server, but not STUN domain, because the phone will query the DNS-SRV record from outbound domain(to know UDP or TCP), but not STUN domain. We only query A record from STUN domain(to know the Address).
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