[Freeswitch-users] Refer with replaces - how to configure to support

Magnus Kelly magnus.kelly at gmail.com
Sun Jun 25 21:10:55 UTC 2017


Hello All,
Further to prior question on support for Refer with replaces configuration
question - the ladder diagram below is the desired sequence - currently
fails at line 45
This is one of the call cases required to interop with MS Skype4Biz of
which I am curious if this can be handled as it seems the Refer C target is
not revealed until after the "parking" Invite is sent
Example Refer is below

   ------------------------------------------------------------------------
   REFER sip:gw+s4btrunk at 10.113.3.4:5066;transport=udp;gw=s4btrunk SIP/2.0
   FROM: <sip:+4419xxxxxxxx at 10.113.8.32:5068
;transport=tcp>;epid=ED60F08DC5;tag=6acfb33460
   TO: <sip:+4414xxxxxxxx;transport=udp at 193.113.106.226>;tag=r3cp3tF36UmZg
   CSEQ: 2 REFER
   CALL-ID: 78dff094-ca55-1235-8c91-000c29a74006
   MAX-FORWARDS: 70
   VIA: SIP/2.0/TCP 10.113.8.32:5068;branch=z9hG4bK433d335f
   CONTACT: <sip:skype4biz.xxxxxxxxx.co.uk:5068
;transport=Tcp;maddr=10.113.8.32;ms-opaque=1befc8e31af6a72f>
   CONTENT-LENGTH: 0
   REFER-TO: <sip:skype4biz.xxxxxxxxx.co.uk:5068
;transport=Tcp;maddr=10.113.8.32;ms-opaque=1befc8e31af6a72f?REPLACES=d71cf52b-2961-4b3c-b823-73191c204d39%3Bfrom-tag%3D58af409ce4%3Bto-tag%3Dd6814c6feb>
   USER-AGENT: RTCC/6.0.0.0 MediationServer
   ------------------------------------------------------------------------




1PSTN 2                    S4B/Mediation Server
  PSTN/FS1 -IN
2         |                                  |
                  |
3         |                                  |     (1) INVITE
                 |
4         |
 |<----------------------------------------------|
5         |                                  |
                  |
6         |                                  |     (2) 100 Trying
                 |
7         |
 |---------------------------------------------->|
8         |                                  |
                  |
9         |                                  |     (3) 183 Session Progress
(Dialog 1)       |
10        |
 |---------------------------------------------->|
11        |                                  |
                  |
12        |                                  |     (4) PRACK
                  |
13        |
 |<----------------------------------------------|
14        |                                  |
                  |
15        |                                  |     (5) 200 OK (PRACK)
                 |
16        |
 |---------------------------------------------->|
17        |                                  |
                  |
18        |                                  |         Early Media
                  |
19        |
 |==============================================>|
20        |                                  |
                  |
21        |                                  |     (6) 200 OK (Dialog 1)
                  |
22        |
 |---------------------------------------------->|
23        |                                  |
                  |
24        |                                  |     (7) ACK
                  |
25        |
 |<----------------------------------------------|
26        |                                  |
                  |
27        |                                  |         Bidirectional RTP
                  |
28        |
 |<=============================================>|
29        |                                  |
                  |
30        |                                  |     (8) INVITE(Hold)
                 |
31        |
 |---------------------------------------------->|
32        |                                  |
                  |
33        |                                  |     (9) 200 OK (hold)
                  |
34        |
 |<----------------------------------------------|
35        |                                  |
                  |
36        |                                  |     (10) ACK
                 |
37        |
 |---------------------------------------------->|
38        |                                  |
                  |
39        |                                  |     (11) REFER
                 |
40        |
 |---------------------------------------------->|
41        |                                  |
                  |
42        |                                  |     (12) 202 Accepted
(OK till here)      |
43        |
 |<----------------------------------------------|
44        |                                  |
                  |
45        |                                  |     (13) INVITE(Replaces,
Dialog 2) (Not sent)|
46        |
 |<----------------------------------------------|
47        |                                  |
                  |
48        |                                  |     (14) 183 Session
Progress(Dialog 2)       |
49        |
 |---------------------------------------------->|
50        |                                  |
                  |
51        |                                  |     (15) NOTIFY (Trying)
                 |
52        |
 |<----------------------------------------------|
53        |                                  |
                  |
54        |                                  |     (16) 200 OK (NOTIFY)
                 |
55        |
 |---------------------------------------------->|
56        |                                  |
                  |
57        |   (17) INVITE(Dialog 3)          |
                  |
58        |<---------------------------------|
                  |
59        |                                  |
                  |
60        |   (18) 183 Session Progress      |
                  |
61        |--------------------------------->|
                  |
62        |                                  |
                  |
63        |                                  |     (19) 183 Session
Progress(Dialog 2)       |
64        |
 |---------------------------------------------->|
65        |                                  |
                  |
66        |                                  |     (20) NOTIFY (Trying)
                 |
67        |
 |<----------------------------------------------|
68        |                                  |
                  |
69        |                                  |     (21) 200 OK (NOTIFY)
                 |
70        |
 |---------------------------------------------->|
71        |                                  |
                  |
72        |   (22) 200 OK(Dialog 3)          |
                  |
73        |--------------------------------->|
                  |
74        |                                  |
                  |
75        |                                  |     (23) 200 OK(Dialog 2)
                  |
76        |
 |---------------------------------------------->|
77        |                                  |
                  |
78        |                                  |     (24) NOTIFY
                  |
79        |
 |<----------------------------------------------|
80        |                                  |
                  |
81        |                                  |     (25) 200 OK (NOTIFY)
                 |
82        |
 |---------------------------------------------->|
83        |                                  |
                  |
84        |                                  |     (26) BYE(Dialog 1)
                 |
85        |
 |<----------------------------------------------|
86        |                                  |
                  |
87        |                                  |     (27) 200 OK (BYE, Dialog
1)               |
88        |
 |---------------------------------------------->|

On 25 June 2017 at 17:14, Magnus Kelly <magnus.kelly at gmail.com> wrote:

> Hello all,
>
> I am trying to configure the FS dial plan to fully support "Refer with
> Replaces" ?
>
> Call case is FS establishes the call successfully with an upstream server,
> but when the user behind the upstream server performs a transfer, a Refer
> with replaces is generated and sent to FS, FS accepts the request, but post
> the 202 the expected invite (FS to upstream) in support of replaces does
> not occur and then the transfer fails.
>
> My assumption is I am missing the correct configuration for Refer with
> Replaces, I have spent some time searching web but not yet found the
> correct way to handle this. My assumption is FS fully supports "Refer with
> Replaces" but confirmation and any tips on configuration most welcome.
>
> Appreciate any insight.
>
> Thanks
> Magnus
>
>
>
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