[EMAIL PROTECTED] wrote: > We (Pingtel) are running into an increasing number of customers who > are having trouble with PSTN gateways. Specifically, they want to use > more than one PSTN gateway, but it's difficult to have a proxy route > calls reliably through multiple gateways, as there is no reliable rule > to distinguish when a gateway returns a failure because it has no > available lines vs. a failure at the destination phone.
Did you look at TGREP? ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-ietf-iptel-tgrep-08.txt > > In principle, a gateway should return 486 if the PSTN reports that the > destination phone is busy, and return 503 if the gateway has no > available lines. But some gateways return 486 for no-available-line. > > Worse, if the gateway is accessed through an intermediate proxy, a 503 > response will be converted to 500 by the intermediate gateway (RFC > 3261, section 16.7, step 6). And 500 is used to indicate quite a > number of conditions (including "CSeq out of order"), as well as being > allowed to mean "internal server error (not otherwise classified)".. > > As far as I can see, the way out of this mess is to have a more clear > distinction of failure codes that mean the call failed at the > destination UA vs. failure codes that mean the call failed during some > transport step. This isn't all that difficult, but to make it work, > we need to build a consensus. > > I've written an Internet-Draft, > draft-worley-sip-redundancy-response-01, making such a classification, > and pointing out the four or so ambuguous failure codes, with > suggestions for splitting thost failure codes into two separate codes. > It's available at > http://svn.resiprocate.org/rep/ietf-drafts/worley/draft-worley-sip-redundancy-response-01.txt > until it gets into the official directories. > > I'd like to start a discussion between proxy builders and gateway > builders to establish a set of conventions that will work well in > practice. > > Dale > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > -- Marc Petit-Huguenin [ ] Home: [EMAIL PROTECTED] [RFC1855-compliant space for rent ] Work: [EMAIL PROTECTED] [ ] _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
