IEEE Network • November/December 2009
0890-8044/09/$25.00 © 2009 IEEE
owadays, multimedia services are presented in
multiple analyses as the key point for future
communications. This trend, together with the
confluence of different types of services, termi-
nals, and networks into a unique next-generation network
(NGN), will allow the incorporation of wideband applications.
NGN is a packet-based network able to provide telecom-
munication services to users and make use of multiple broad-
band quality of service (QoS)-enabled transport technologies,
and in which service-related functions are independent of the
underlying transport-related technologies .
Currently, the most relevant NGN standardization initia-
tives (European Telecommunications Standards Institute
[ETSI] and Third Generation Partnership Project [3GPP])
are focused on the regularization of these emerging infras-
tructures . 3GPP has defined a first approach to the
NGN architecture in the mobile world through the IP multi-
media subsystem (IMS), which is now considered the stan-
dard for real-time multimedia communication services.
However, ETSI Telecommunications and Internet Con-
verged Services and Protocols for Advanced Networking
(TISPAN) is working on the adaptation of IMS to offer
these kinds of services through fixed access networks. This
solution will contribute to overcome all the restrictions of
service delivery in current platforms, avoiding the use of
proprietary solutions and the lack of competence in the
field of open service platforms.
NGN is based on an open architecture of standardized lay-
ers with guaranteed QoS, security, mobility, and flexible ser-
vice platforms; therefore, it appears as a suitable option for
achieving pan-European communication, since it is presented
as an integrated solution that can bring users the benefits of a
seamless and solid user experience regardless of their loca-
Mass market uptake of new services offered by such a plat-
form requires interoperability between operators. Only a
small number of network equipment providers are actually in
a position to really offer an end-to-end integrated telecommu-
nications solution applying the NGN specifications. Each of
these providers has its own proprietary solution, and they are
not prepared enough to be interconnected to equipment from
different providers since they apply different implementations
of the standard. Also, the specifications themselves are diffi-
cult to keep track of, as several major specification bodies are
involved, producing hundreds of documents.
Due to these facts, even simple a priori tasks such as a
basic call or a client registration are far from being out-of-the-
box features, requiring hardware and software adaptations
that may or may not be technically feasible. Once basic net-
working interoperability is achieved, additional challenges
such as integration with existing systems, multivendor service
layer interoperability, and mobility of users and terminals
must be addressed too.
Different research programs have appeared in order to
Javier M. Aguiar, Carlos García, and Henar Vega, Universidad de Valladolid
Álvaro Martínez and Tamara de Vega, Telefónica I+D
Philippe Bouillé, France Telecom R&D
Antoine de Poorter, Ericsson Spain
This article presents an open and functional architecture based on a next-genera-
tion network solution in order to seize its converged nature to guarantee interoper-
ability among different platforms and terminals. The defined architecture is an
integrated solution for end-to-end communication of various IP multimedia subsys-
tem platforms marketed by different vendors, belonging to several operators locat-
ed in different countries across Europe and supporting multiple terminals and
technologies in order to experiment with a new broadband telephony service for
the residential environment. This work addresses, in particular, the interoperability
problems of name resolution and implementation of the Session Initiation Protocol
Interface at the terminal as a key use in such a scenario. Also, several advanced
services are developed and tested within the proposed architecture as a proof of
concept of the IMS capability for quick service creation and deployment. The archi-
tecture proposed contributes to the reduction of obstacles and barriers among the
European countries in order to adopt NGN architectures, allowing a new type of
communication that is more complete and flexible.
Multimedia Services Interoperability in
Next-Generation Networks for the
IEEE Network • November/December 2009
based on interconnected NGN platforms. Also, several
advanced services were developed within the project, which
illustrate the quick service development — independent of
transport and network layer — promised by IMS.
In summary, MaCS settled some of the grounds for the
development of a pan-European communication platform for
the fixed networks domain based on the guidelines established
by the IMS infrastructure for the mobile environment.
When the MaCS Project started, no IMS platform was in
commercial service by a fixed operator. Nowadays, IMS is
being adopted as the only reference architecture for a con-
verged fixed/mobile network. The initial steps to interoperable
solutions taken within the project have granted leading mar-
ket positions to the partners involved for IMS deployment
and manufacturing of terminals and network equipment, and
the project has contributed significantly to the development of
commercial IMS products, new multimedia terminals, and
innovative services. Consequently, user experience will be
enriched through a plethora of advanced services that will
stimulate a new way of communication.
The present article is based on work undertaken in the
Multimedia Communication Service (MaCS) Project,
whose consortium the authors want to acknowledge. The
project was launched under the Cooperation for a Sus-
tained European Leadership in Telecommunications
(CELTIC) initiative, a EUREKA cluster program, sup-
ported by most of the major European players in commu-
 ITU-T Rec. Y.2001, “General Overview of NGN,” Dec. 2004.
 C.-S. Lee and D. Knight, “Realization of the Next-Generation Network,” IEEE
Commun. Mag., vol. 43, no. 10, Oct. 2005, pp. 34–41.
 CELTIC Initiative, “Multimedia Communication Service (MaCS),”Project no.:
CP1-030, accessed May 2009; http://www.celticinitiative.org/projects/macs
 “The MaCS Project,” 1st INCCOM Wksp., Valladolid, Spain, May 11–12,
 A. Sanchez, B. Carro, and S. Wesner, “Telco Services for End Customers: Euro-
pean Perspective,” IEEE Commun. Mag., vol. 46, no. 2, Feb. 2008, pp. 14–18.
 K. Knightson, N. Morita, and T. Towle, “NGN Architecture: Generic Princi-
ples, Functional Architecture, and Implementation,” IEEE Commun. Mag., vol.
43, no. 10, Oct. 2005, pp. 49–56.
 D. Geer, “Building Converged Networks with IMS Technology,” IEEE Comput-
er, vol. 38, no. 11, Nov. 2005, pp. 14–16.
 H. Schulzrinne and J. Rosenberg, “The Session Initiation Protocol: Internet-Centric
Signaling,” IEEE Commun. Mag., vol. 38, no. 10, Oct. 2000, pp. 134–41.
 J. M. Aguiar et al., “QoS of Multiparty Videoconference over Geostationary
Satellites,” Proc. QoS ‘04, London, U.K., Mar. 2004.
JAVIER M. AGUIAR (firstname.lastname@example.org) holds a Ph.D. in telecommunications and
telecommunications engineering from the University of Valladolid, Spain. Cur-
rently he is a professor with the Higher Technical School of Telecommunications
Engineering at the University of Valladolid, and his research is focused on next-
generation networks and services. He participated in IST FP5 (ICEBERGS), IST
FP6 (MEDIANET, SATSIX, OPUCE), EUREKA-CELTIC (MaCS, QUAR2, IMAGES,
PABlOS), and ESA (AO4694), managing technical activities in national and
European research projects, as well as cooperation with relevant companies in
the telecommunications sector. Furthermore, he has contributed in the standard-
ization field as an expert in Specialist Task Force 294 of the European Telecom-
munications Standards Institute.
CARLOS GARCIA (email@example.com) holds an M.Eng. degree in telecom-
munications engineering from the University of Valladolid, where he is also a
Ph.D. candidate. He has been involved in several national and European R&D
projects, including IST FP6 SATSIX and IST FP6 OPUCE, as well as several
CELTIC Initiative projects (MaCS, QUAR2, IMAGES) and national projects. His
research activities include service engineering, virtualization middleware, context-
aware services and applications, QoS provisioning, and applications over next-
HENAR VEGA (firstname.lastname@example.org) holds an M.Eng. degree in telecommu-
nications engineering from the University of Valladolid, where she is also a Ph.D.
candidate. She has been involved in several national and European R&D pro-
jects, including IST FP5 MEDIANET, EUREKA CELTIC QUAR2, and EUREKA
CELTIC IMAGES. Her research interests include QoS measurement and provision-
ing in multimedia communications, VoIP, and NGN architectures.
ÁLVARO MARTINEZ (email@example.com) works as an R&D engineer at Telefónica I+D
since 1999, focused on services, software engineering, IP and NGN networks,
Web and voice over IP pre-commercial services, applications, platforms, and ter-
minals applied research and development for the Telefonica Group. Nowadays,
he works in open research and collaborative European innovation projects, tar-
geting residential, SME, and community customers.
TAMARA DE VEGA (firstname.lastname@example.org) graduated in 2002 with an M.Eng. in telecom-
munications engineering from the University of Valladolid. She has been an R&D
engineer at Telefónica I+D since 2002, involved in several national and Euro-
pean R&D projects related to service engineering, IP and NGN networks, and
voice over IP applications, platforms, and terminals.
PHILIPPE BOUILLÉ (email@example.com) graduated in 1991 in
electronics engineering from the National Institute of Applied Science (INSA),
France. He has been working for France Telecom R&D since 1993 and is in
charge of next-generation services developments for the company. He has partic-
ipated in several NGN service deployment projects since 2000 and participates
actively in related ETSI standardization tasks. His work areas include NGN ser-
vices, architectures and protocols, deployment strategies, business models, stan-
dardization, and qualification.
ANTOINE DE POORTER (firstname.lastname@example.org) has wide experience,
over nearly 20 years, working with wireless telephony systems, especially mobile
systems. He has worked with analog mobile systems, then GSM, and later UMTS.
Currently he works at the Ericsson Spain R&D Main Centre as a master systems
engineer. His main areas of competence are related to network user databases,
mobile network security, mobile multimedia systems, and 3G applications.