My 2 cents First sending multiple 180 with the same tags is completely valid. Second, IMO a 183 would be a good answer for this. the only thing to be careful here is if whether the voice has been cut already or not by MGW. if it has not, then 183 wo/SDP should be good enough if the voice has been cut already. you need to send 183 w/SDP (same one ).
Other thing also i would have expected that MSC-A would have sent a CPG(PI=call being forwarded) . hope this helps Cheer alejandro On Tue, May 12, 2009 at 4:55 AM, Kapil Saxena < kapil.sax...@dilithiumnetworks.com> wrote: > I have a MGW that has SIP interface towards UE and ISUP towards MSC. > > For a SIP->ISUP call: > > 1. MGW receives SIP INVITE from UE and sends IAM to MSC-A. > 2. MGW receives backward ACM message with "called party status = free" > from MSC-A. > 3. MGW sends 180 Ringing towards SIP UE. > 4. Called Party (on MSC-A) rings but does not answer > 5. Call is now forwarded by MSC-A (this is the case of call forwarding > after alerting the user) towards MSC-B. Thus, MSC-A sends IAM to MSC-B > 6. MSC-B sends ACM message with "called party status = free" towards > MSC-A > 7. MSC-A transforms it to CPG (Alerting) and sends it towards MGW. > 8. My question is: what MGW should do with 2nd CPG (Alerting) message? > RFC 3398 (ISUP<->SIP interworking) mandates to send out 180 but as MGW has > already sent out 180 (see #3 above), so it can not send duplicate 180 with > same "tag". > > Thanks > Kapil Saxena > > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
