■■ All ITU-T NG networks (such as ISDN, BISDN/ATM, IMS/NGN/IP)
are based on grand designs and are not based on a continuous evolu-
tion. The changes from TDM to ATM to IP are significant discontinu-
ities in the ITU-T architectures.
The authors of this book fully share the IETF view that NGN and IMS are
technically a protocol layer violation (application-aware networks). Such net-
works are, therefore, not scalable and may collapse under their own weight or
from sheer complexity or for various technical reasons.
Moreover, we believe that the central control in NGN and IMS takes the con-
trol away from users and will fail in the open market where users have a
choice. For example, someone using Google, Yahoo!, or MSN to search for a
product and then going to Amazon.com or eBay to buy it, may want to use the
voice services of those companies and not be restrained in any way by the con-
straints imposed by IMS or NGN services.
Summary
SIP has all the marks of a thoroughly disruptive technology. It will fundamen-
tally change communication services as we know them today and also the
communication habits of users [36]. The complete integration of communica-
tions with the web and e-mail has thus started and much innovation and the
resulting new services are still ahead. SIP and its related protocols prove to be
the enabling ingredients for new communications, much like its model proto-
col HTTP 1.1 was to the World Wide Web.
Chapter 21, “Conclusions and Future Directions,” summarizes the informa-
tion on future work and current directions for IP communications.
References
[1] Newtons’ Telecomm Dictionary. 21st Edition. CMP Books, 2005.
[2] The search index page for IETF RFCs is http://www.rfc-editor.org/
rfcsearch.html.
[3] The True Picture of Peer-to-Peer Filesharing: http://www.cachelogic.com/
research/slide1.php.
[4] Internet usage statistics: http://www.sims.berkeley.edu/research/
projects/how-much-info-2003/internet.htm.
[5] Nimcat Networks at: http://www.nimcatnetworks.com/Products.aspx.
[6] Peerio (“Because people don’t need servers”) at http://peerio.com.
[7] “A Presence Event Package for SIP” by J. Rosenberg. RFC 3856, IETF,
August 2004.
[8] “Indication of Message Composition for Instant Messaging” by H.
Schulzrinne, RFC 3994, January 2005.
Internet Communications Enabled by SIP 35