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D375 not doing SRV lookup


has behaviour changed with regard to SRV lookup.  I am testing a D375 running firmware  snomD375-SIP

With previous snom models (3xx and 7xx), and in the absence of a NAPTR record, the phones would look for SRV records in the following order:

We have been using this on some domains to prioritise registration over TCP.

With the D375 it only tries to fetch the record.

If we add a NAPTR record then it will be fetched correctly and then the D375 will grab and use the SRV records as listed in the NAPTR.

At present we would need to add a NAPTR record for each customer domain, before we can deploy the D375 alongside the current functioning 3xx and 7xx phones!

Hello Paul,

thanks for contacting us,

the order in absence of NAPTR record should be SIPS, TCP, UDP also in and D375.

I would like to convert this in a ticket to investigate a bit more.



has there been any follow up to this? I do have a 821 that used to use an A record for the registrar and proxy, which has been changed to SRV records only (the A record doesn't resolve to an IP any longer). 

The 821 shows the SRV records in the DNS cache but fails to register correctly.



Hi Marko,

can you provide more informations about your DNS setup ? please provide an example of your NAPRT, SRV and A records of your SIP domain.


Hi Pietro,

so the 821 is set to use


Outbound Proxy:

host -t ANY for that gives: has NAPTR record 0 0 "s" "SIPS+D2T" "" has NAPTR record 1 0 "s" "SIP+D2T" "" has NAPTR record 2 0 "s" "SIP+D2U" ""

But with that registar / proxy set, the phone doesn't register, even though the DNS Cache page clearly shows it knows about those NAPTR records. 

There is no A record anymore for

Thanks for your help!

I see the SRV records for is resolving with: 3599  IN  SRV  1 0 5060

and then the A record for is (

Anyway we need to investigate a bit more on that issue. I'll convert this topic in a ticket.

That's absolutely correct and my wording wasn't clear on that, sorry about that. 

Just so you know - if I use the IP to which resolves, registration works fine.

Let me know if you need any other details.



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