On Thu, 2009-08-20 at 16:49 +0800, jun,wen wrote:
> Hi, Team,
>  
> I am trying to implement a blacklist to users to bar some specific
> call destination. when created a permission of "Blacklist
> Access", I  made a new dial plan of "Blacklist" with specific barred
> PSTN number by a prefix and checked the "Blacklist Access" as the
> required permissions . 
>  
> After done this, when I made a PSTN outgoing call with that prefix,
> sipx stopped that call with "482 Loop Detected with 2 hops ago, with
> Sipfrag", is it the designed behavior of sipx on this secnario ? When
> I looked at the Permission of Users, whatever I checked the box of
> Blacklist Access or not, calls to the specific destination number were
> always blocked with the same reason code. How then to make the
> override ?

Did you put a gateway in that Blacklist dial plan?

If you don't specify a gateway in a dial plan, then implicitly the call
is sent back to the proxy again.  This is called a 'spiral' and is very
useful for rewriting internal numbers to and from external forms (for
example, match your DID prefix digits followed by the extension and
rewrite them to just the extension, or the other way around).  Since you
didn't change the number, then the same rule applies on the spiraled
request, and eventually the hop limit mechanism detects the error and
stops the call.

(The sipfrag body on the loop detected error response is a diagnostic
mechanism - it allows anyone looking at the trace to see what the
message looked like when it ran out of hops, which can help a lot in
figuring out how it got there.  For details, see
http://tinyurl.com/nwmnhu)


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