Denis, Comment below.
John > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On Behalf Of Alexeitsev, D > Sent: 22 February 2008 16:08 > To: [email protected] > Subject: [BLISS] Recall INVITE identification > > Hi > > Problem description. > > On the receipt of the ready for recall notification the > caller send the recall INVITE to the callee. The CC monitor > shall be able to recognise that the incoming INVITE is the > recall. Otherwise the INVITE will be rejected. > > The CC monitor shall also be able to recognise the > relationship between the SUBSCRIBE request for the CC > monitoring and the initial INVITE. > > 3 methods have been discussed for the purpose of recall > identification: > > A) Recall INVITE and SUBSCRIBE for CC monitoring shall have > the same Call-Id as the initial INVITE. > Advantage: This method works in the open SIP space. > Disadvantage: The method does not work in the > distributed gateway environment where a recall INVITE can be > generated by the different gateway, as > the one that send the initial invite. [JRE] This will not work if there is an intermediate B2BUA that does not maintain call-ID between the upstream side and the downstream side. > > B) Recall INVITE and SUBSCRIBE for CC monitoring shall have > the constructed hash of the caller and callee's E.164 number > as the Request-URI 'id' parameter. > > Advantage: This method overcomes the gateway > problem as the caller and callee address information stays > the same for initial and recall call > even if the relevant INVITEs were generated by different > gateways. The anonymity of the caller is preserved by using > the hash over his number. Works in the > open SIP environment. > > Disadvantage: Additional complexity of implementing > the hash function, especially relevant for the gateways. > Every INVITE has to have the 'id'. > > > C) Recall INVITE and SUBSCRIBE for CC monitoring shall have > the concatenation of the caller and callee's E.164 number, in > the 'id' parameter without hash (simplified B solution). > > Advantage: For systems, that want to avoid the > complexity of hashing. > Disadvantage: Works only in trusted environments, > as the caller identity is revealed in the 'id' parameter. > > All three methods to identify the recall INVITE and SUBSCRIBE > for CC monitoring can be used by the CC monitor in parallel. > The decision to use a particular method can be done by the CC > monitor by analysing the trust relationship with the caller domain. > > > Comments are very welcomed. > > Greetings > Denis Alexeitsev > > _______________________________________________ BLISS mailing list [email protected] http://www.ietf.org/mailman/listinfo/bliss
