No subject


Wed Jun 27 05:48:46 CEST 2012


Bob=3DCaller
Alice=3DCalled
John=3DTransfer party


1)    Bob calls Alice. The usual INVITE,Trying,200 OK, ACK.

2)    Alice transfers the call to John using Re-INVITE.

a.    Alice calls John. The usual INVITE,Trying,200 OK, ACK.

b.    Alice Re-INVITEs Bob using INVITE with adjusted SDP.

3)    Bob is connected to John through Alice in some magical way. I'm guess=
ing because the SDP has been changed and for some reason the RTP stream flo=
ws between Bob and John through Alice?

Is this correct? If not, perhaps someone could explain it to me from scratc=
h.

Maybe useful to know that we are using Cisco equipment for call handling (V=
XML and TCL scripts).

Thanks,

Grant

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</o:shapelayout></xml><![endif]--></head><body lang=3DNL link=3Dblue vlink=
=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span style=3D'fon=
t-size:10.0pt;font-family:"Verdana","sans-serif"'>Hello,<o:p></o:p></span><=
/p><p class=3DMsoNormal><span style=3D'font-size:10.0pt;font-family:"Verdan=
a","sans-serif"'><o:p>&nbsp;</o:p></span></p><p class=3DMsoNormal><span lan=
g=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'>I&#=
8217;ve been searching the internet to find an explanation on how SIP trans=
fer works using Re-INVITE and/or UPDATE, but I can&#8217;t seem to find a g=
ood source.<o:p></o:p></span></p><p class=3DMsoNormal><span lang=3DEN-US st=
yle=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p>&nbsp;</o:=
p></span></p><p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:10.=
0pt;font-family:"Verdana","sans-serif"'>From what I understand(and this is =
the way we do it), the following happens:<o:p></o:p></span></p><p class=3DM=
soNormal><span lang=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana"=
,"sans-serif"'><o:p>&nbsp;</o:p></span></p><p class=3DMsoNormal><span lang=
=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'>Bob=
=3DCaller<o:p></o:p></span></p><p class=3DMsoNormal><span lang=3DEN-US styl=
e=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'>Alice=3DCalled<o:=
p></o:p></span></p><p class=3DMsoNormal><span lang=3DEN-US style=3D'font-si=
ze:10.0pt;font-family:"Verdana","sans-serif"'>John=3DTransfer party<o:p></o=
:p></span></p><p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:10=
.0pt;font-family:"Verdana","sans-serif"'><o:p>&nbsp;</o:p></span></p><p cla=
ss=3DMsoListParagraph style=3D'text-indent:-18.0pt;mso-list:l0 level1 lfo1'=
><![if !supportLists]><span lang=3DEN-US style=3D'font-size:10.0pt;font-fam=
ily:"Verdana","sans-serif"'><span style=3D'mso-list:Ignore'>1)<span style=
=3D'font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; </span></span></span><=
![endif]><span lang=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana"=
,"sans-serif"'>Bob calls Alice. The usual INVITE,Trying,200 OK, ACK.<o:p></=
o:p></span></p><p class=3DMsoListParagraph style=3D'text-indent:-18.0pt;mso=
-list:l0 level1 lfo1'><![if !supportLists]><span lang=3DEN-US style=3D'font=
-size:10.0pt;font-family:"Verdana","sans-serif"'><span style=3D'mso-list:Ig=
nore'>2)<span style=3D'font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; </s=
pan></span></span><![endif]><span lang=3DEN-US style=3D'font-size:10.0pt;fo=
nt-family:"Verdana","sans-serif"'>Alice transfers the call to John using Re=
-INVITE. <o:p></o:p></span></p><p class=3DMsoListParagraph style=3D'margin-=
left:72.0pt;text-indent:-18.0pt;mso-list:l0 level2 lfo1'><![if !supportList=
s]><span lang=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans=
-serif"'><span style=3D'mso-list:Ignore'>a.<span style=3D'font:7.0pt "Times=
 New Roman"'>&nbsp;&nbsp;&nbsp; </span></span></span><![endif]><span lang=
=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'>Alic=
e calls John. The usual INVITE,Trying,200 OK, ACK.<o:p></o:p></span></p><p =
class=3DMsoListParagraph style=3D'margin-left:72.0pt;text-indent:-18.0pt;ms=
o-list:l0 level2 lfo1'><![if !supportLists]><span lang=3DEN-US style=3D'fon=
t-size:10.0pt;font-family:"Verdana","sans-serif"'><span style=3D'mso-list:I=
gnore'>b.<span style=3D'font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; </=
span></span></span><![endif]><span lang=3DEN-US style=3D'font-size:10.0pt;f=
ont-family:"Verdana","sans-serif"'>Alice Re-INVITEs Bob using INVITE with a=
djusted SDP.<o:p></o:p></span></p><p class=3DMsoListParagraph style=3D'text=
-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span lang=3D=
EN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'><span s=
tyle=3D'mso-list:Ignore'>3)<span style=3D'font:7.0pt "Times New Roman"'>&nb=
sp;&nbsp;&nbsp; </span></span></span><![endif]><span lang=3DEN-US style=3D'=
font-size:10.0pt;font-family:"Verdana","sans-serif"'>Bob is connected to Jo=
hn through Alice in some magical way. I&#8217;m guessing because the SDP ha=
s been changed and for some reason the RTP stream flows between Bob and Joh=
n through Alice?<o:p></o:p></span></p><p class=3DMsoNormal><span lang=3DEN-=
US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p>&nbsp=
;</o:p></span></p><p class=3DMsoNormal><span lang=3DEN-US style=3D'font-siz=
e:10.0pt;font-family:"Verdana","sans-serif"'>Is this correct? If not, perha=
ps someone could explain it to me from scratch.<o:p></o:p></span></p><p cla=
ss=3DMsoNormal><span lang=3DEN-US style=3D'font-size:10.0pt;font-family:"Ve=
rdana","sans-serif"'><o:p>&nbsp;</o:p></span></p><p class=3DMsoNormal><span=
 lang=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'=
>Maybe useful to know that we are using Cisco equipment for call handling (=
VXML and TCL scripts).<o:p></o:p></span></p><p class=3DMsoNormal><span lang=
=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","sans-serif"'><o:p=
>&nbsp;</o:p></span></p><p class=3DMsoNormal><span lang=3DEN-US style=3D'fo=
nt-size:10.0pt;font-family:"Verdana","sans-serif"'>Thanks,<o:p></o:p></span=
></p><p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:10.0pt;font=
-family:"Verdana","sans-serif"'><o:p>&nbsp;</o:p></span></p><p class=3DMsoN=
ormal><span lang=3DEN-US style=3D'font-size:10.0pt;font-family:"Verdana","s=
ans-serif"'>Grant<o:p></o:p></span></p></div></body></html>=

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