Hi Alex, The Alert-Info header field specifies an alternative ringback tone to the UAC. This is done by including a URI in the Alert-Info header field, that specifies the tone.The URI is most commonly the HTTP URL to the audio file.
As per both usability and ABNF grammer, absolute URI is mandatory in Alert Info. I am not sure if there is any SIP Stack is lenient about it. Thanks, Alok Tiwari On Tue, May 12, 2015 at 6:42 AM, Alex Balashov <abalas...@evaristesys.com> wrote: > Hello, > > The ABNF grammar for Alert-Info is: > > Alert-Info = "Alert-Info" HCOLON alert-param *(COMMA alert-param) > alert-param = LAQUOT absoluteURI RAQUOT *( SEMI generic-param ) > > I have an application that seems to utilise just a generic-param without a > URI. However, I don't see any */? quantifiers for absoluteURI which suggest > that it's optional: > > absoluteURI = scheme ":" ( hier-part / opaque-part ) > > Maybe it's a failure on my part to properly understand ABNF, however. > > My fundamental question is: is there any grammatically acceptable way to > have an Alert-Info header value consisting of no URI and just a > generic-param, e.g. > > Alert-Info: ;internal=xyz > Alert-Info: <>;internal=xyz > > Thanks! > > -- Alex > > -- > Alex Balashov | Principal | Evariste Systems LLC > 303 Perimeter Center North, Suite 300 > Atlanta, GA 30346 > United States > > Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct) > Web: http://www.evaristesys.com/, http://www.csrpswitch.com/ > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > -- Alok Tiwari | Consultant GlobalLogic P +91.120.406.2000 x 2477 M +91.991.034.7139 S alo...@globallogic.com <http://alok.t_globallogic.com/> www.globallogic.com <http://www.globallogic.com/> http://www.globallogic.com/email_disclaimer.txt _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
