[OpenSIPS-Users] tm module CANCEL reason on timeout

[John Quick]

Bogdan,

I think your AVP implementation would be very useful. Thanks.

"From SIP reply codes perspective there is no difference between timeout
with replies and timeout with none" - I dislike this, but that does not mean
it is wrong!

It seems illogical to me - what is the point of having available a large
pool of SIP Response codes (some of which are rarely used) and then using
the same one to show two completely different results. This has caused me
problems when trying to detect a "failed" downstream server or network path.
I had to write extra code in my failure_route just to help identify which of
these two outcomes has happened when status is 408.

Best regards,

John Quick


-----Original Message-----
From: Bogdan-Andrei Iancu [mailto:bogdan at opensips.org] 
Sent: 25 October 2012 14:34
To: john.quick at smartvox.co.uk
Cc: 'OpenSIPS users mailling list'
Subject: Re: [OpenSIPS-Users] tm module CANCEL reason on timeout

Hi John,

 From SIP reply codes perspective there is no difference between timeout
with replies or timeout without replies - you all the time get the 408 (at
least this is what I know :) ).

The difference is only in the reason code.

Now about the implementation - if using AVPs, you will have to provide let's
say the full Reason hdr (name, value, EOH) so you could put actually more
headers in the AVP (it will be handled like a string to appended to
headers). If there is no such AVP, we will use the internal default one.

Regards,

Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
http://www.opensips-solutions.com


On 10/25/2012 03:37 PM, John Quick wrote:
> Hi Bogdan,
>
> It is interesting that RFC3398 recommends mapping ISUP 19 to SIP 480. 
> I think this makes sense and so I agree with your logic. It is good to 
> use two different response values, one for "timeout" (no response) and 
> another for "ring-no-answer" (where a 180 response has been received) 
> because these are two completely different conditions.
>
> However, doesn't this mean that there is an inconsistency elsewhere in 
> OpenSIPS?
> If I understand correctly, the timers in the tm module operate as follows:
> "timeout" (no response) is linked to fr_timer "ring-no-answer" is 
> linked to fr_inv_timer.
>
> Yet, the tm module always generates the same SIP response, 408, for 
> both fr_timer and for fr_inv_timer. Should it not generate 408 for 
> fr_timer and
> 480 for fr_inv_timer?
>
> Regarding your suggestions for controlling the reason phrase within 
> the tm module, I would say that both methods look satisfactory. The 
> AVP is probably the more straightforward for users. However, I have 
> just found the following information in RFC3326:
> "A SIP message MAY contain more than one Reason value (i.e., multiple
>     Reason lines), but all of them MUST have different protocol values
>     (e.g., one SIP and another Q.850)."
>
> If it were added to the tm module, would the "reason cause" AVP allow 
> the addition of multiple "Reason" headers?
>
> John
>
> -----Original Message-----
> From: Bogdan-Andrei Iancu [mailto:bogdan at opensips.org]
> Sent: 25 October 2012 12:41
> To: john.quick at smartvox.co.uk; OpenSIPS users mailling list
> Subject: Re: [OpenSIPS-Users] tm module CANCEL reason on timeout
>
> Hi John,
>
> The 480 code is on purpose. See the mapping between Q.850 and SIP for
> reasons:
>
> https://support.net.com/display/VXDOC471/Mapping+Q.850+to+SIP+Responses
>      or:
>
> wiki.freeswitch.org/index.php?title=Special:PdfPrint&page=Hangup_Cause
> s
>
> So, if you have a TIMEOUT with no reply, you should report a 408, but 
> if there is timeout with reply, it should be 480. And as in SIP you 
> generate CANCEL only for timeouts with replies ->  it;s 480.
>
> Please correct me if my logic is wrong.
>
> On controlling the Reason phrase in Cancel, this is a bit tricky, as 
> CANCELs are internally generated (on timer) and you have no script 
> interaction. I see 2 approaches here:
>       - make local_route to be trigerred from local CANCELs too, so 
> you can do your own headers
>       - at INVITE time (per branch) set via an AVP the reason hdr to 
> be used (if not default) in case of CANCELing that branch.
>
> Regards,
>
> Bogdan-Andrei Iancu
> OpenSIPS Founder and Developer
> http://www.opensips-solutions.com
>
>
> On 10/22/2012 04:38 PM, John Quick wrote:
>> In "modules/tm/timer.c" function "final_response_handler", a #define 
>> is used to set the Reason header in the CANCEL when triggered by the
> invite timeout.
>> The default is cause=480;text="NO_ANSWER", but I think it should be
>> 408 because 408 is timeout and 480 is temporarily unavailable.
>>
>> I need to be able to control the Reason header when a timeout is 
>> triggered in tm. When the call is being sent to our SS7 gateway, we 
>> need the reason header to be set as follows:
>> Reason: Q.850;cause=19;text="No Answer"
>> When the call is going to a SIP device, I want the header to be like 
>> the current default:
>> Reason: SIP;cause=408;text="NO_ANSWER"
>>
>> Is it permissible to add 2 reason headers or to somehow append 
>> different reasons for different transports to one header?
>>
>> Could the developers put this on the roadmap please - to add 
>> functionality to have more control over the reason header in the tm 
>> module
> on timeout.
>> Many thanks.
>>
>> John Quick
>> Smartvox Limited
>>
>>
>>
>>
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>