Hello Experts, 

I'm working on a problem related to call transfer using REFER scenario. 
Messages flow looks like the following: 
    GW1                  GW2                  GW3
                             INVITE (SDP)
                             --------------->
                             ...
                             200 OK (SDP)       /*let's call it dialog [2-3]*/
                             <---------------
                             ACK
                             --------------->
                             GW2-GW3 media 
                             <==============>
......
 /*GW1 initiates slow start call to GW2*/
 INVITE (w/o SDP)
 --------------------->
  100 Trying
 <---------------------
  REFER 
  (Refer-to: GW3, 
   w/Replaces: [2-3])
 <---------------------
 202 Accepted
 --------------------->
 
  /*GW1 sends slow start INVITE w/Replaces to GW3*/
  INVITE w/Replaces [2-3](w/o SDP)
 ---------------------------------------->
   ..... 

The question is: Doesn't issuing REFER contradicts to any RFC in such a case?
I've run through some of the documents such as RFC3515 and RFC3891, but have 
not 
found any restriction w.r.t. issuing of REFER until 200 OK is received. 
Maybe I miss something?
Really appreciate if someone could help me with this question.

Thanks in advance,
Alexey Entsov
mailto:[email protected]
_______________________________________________
Sip-implementors mailing list
[email protected]
https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors

Reply via email to