34
Introduction
<HNAME VALUE="Proxy-Authorization"/>
</HEADERS>
<TAGS ALLOWED="True"/>
<ALLOWUSERINFOPARAMS ALLOWED="False"/>
<REQUIRENORTELPROFILEHEADER ALLOWED="True"/>
<VIAIP ALLOWED="false"/>
<MAXHEADERS>
<NUM VALUE="20"/>
</MAXHEADERS> <MAXHEADERLENGTH>
<LENGTH VALUE="143"/>
</MAXHEADERLENGTH>
<MAXBLOCKSIZE>
<SIZE VALUE="1375"/>
</MAXBLOCKSIZE>
</SIGNALING>
<MEDIA>
<AUDIOCODECS ALLOWED="True">
<CNAME VALUE="PCMU"/>
<CNAME VALUE="PCMA"/>
<CNAME VALUE="G729"/>
<CNAME VALUE="telephone-event"/>
</AUDIOCODECS>
<VIDEOCODECS ALLOWED="True">
</VIDEOCODECS>
<AUDIOPTIME ALLOWED="True">
<PTIME VALUE="10"/>
<PTIME VALUE="20"/>
</AUDIOPTIME>
<CODECCHANGE ALLOWED="False"/>
<PIVOT ALLOWED="False"/>
<EARLYMEDIA ALLOWED="True"/>
<MULTIPLEPROVISIONALS ALLOWED="True"/>
<ALLCONTENT ALLOWED="True"/>
</MEDIA>
<</DEVICE>
SIP protocol considerations
Application of ringback service call flows
The following SIP interactions relate to ringback call flows:
•
The application of ringback is triggered on reception of an 18x message
from the transfer-to target.
•
If a Session Description Protocol (SDP) is received from the transfer-to
target (at any point, be it initial leg or sequential advance), then the
audio provided by the far end is applied instead of ringback.
•
Network-based ringback is reapplied whenever the far end provides an
18x message with no SDP. Thus, a call that sequentially advances can
have multiple applications of network-based audible ringback.
Nortel Media Application Server
Media Application Server Planning and Engineering
NN42020-201
01.04
Standard
4.0
27 July 2007
Copyright © 2007, Nortel Networks
.
