[Serusers] How can I keep SER from changing reply Response Code from 503 to 500?

[Victor Pascual Ávila]

On Sun, Oct 12, 2008 at 8:49 AM, Martin Hoffmann <hn at nvnc.de> wrote:
>> That said, our SER server knows the given condition sent from
>> a paired PSTN switch is permanent, eg the SIP caller can't
>> call this number via our network now, tomorrow or next week
>> because of who you they or whom their provider is (or what
>> they failed to buy), so in this situation returning 503 all
>> the way out of our network is correct behavior (as stated in
>> the RFC), and doing so allows the upstream entity to click
>> over to the next preferred carrier that might reach that
>> destination.
>
> I think it isn't. Neither 500 nor 503 is a status code for a permanent
> situation. The gateway should return a 4xx class code instead because
> actually this is a client error -- the client is not allowed to call
> this specific number. Sounds like a 403 to me.

I agree with Martin, a 4xx class code should be used instead.

IMO it sounds like an ISUP Cause value "2 no route to destination"
which should be mapped to SIP "404 Not found" (RFC 3398).

Please, correct me if I'm wrong,
-- 
Victor Pascual Ávila