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INTERO - InterOperability Mechanisms for IN/IP Telephony
Journal papers
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Conference papers
Jose Costa-Requena, Ignacio Gonzalez Olias, Raimo Kantola, Nicklas Beijar:
Autoconfiguration
mechanism for IP Telephony Location Servers SCN-IP Telephony convergence
IP Telephony is clearly the service that converges data and real time voice,
video over IP networks. This paper shows that the convergence for this
specific service is feasible. Nevertheless, it shows that certain technologies
trends needs to be solved. The smoothly transition from switched telephony
over IP networks can be achieved. This paper analyses a suitable architecture
and presents specific enhancements to be implemented in the existing IP
Telephony routing protocols. The appropriate auto-configuration and replication
mechanism in the proposed architecture will facilitate the data synchronisation
across switched and IP technologies. This will promote the convergence
of services into IP networks in a seamless manner.
Keywords: Location Servers, Synchronisation, TRIP, SCSP, IP
Telephony, Routing, Auto-configuration.
Thesis
Nicklas Beijar, Distribution of Numbering Information in Interconnected
Circuit and Packet Switched Networks, Espoo 2002
Because of the introduction of Internet Protocol (IP) telephony and the
increasing complexity of the telephony networks, the burden of managing
routing information is growing. Number portability, which allows users
to change operators, locations and services without changing their numbers,
is now being required in many countries. An automatic approach of generating
and distributing routing information is motivated.
This master’s thesis examines the issue of how a
routing protocol can be used to distribute numbering information in an
interconnected circuit and packet switched network. An architecture based
on the Telephony Routing over IP (TRIP) protocol for distributing routing
information is developed.
The first part introduces some of the theory and
literature related to the subject. The principles of routing telephone
calls on the circuit switched network and IP networks are presented. The
TRIP protocol and ENUM (tElephone NUmbering Mapping) directory are major
issues, since they form the base for the architecture. Number portability
and its implementations are described.
In the second part, the solution is developed. The
architecture is defined and some scenarios are presented. A new protocol
named CTRIP (Circuit Telephony Routing Information Protocol) is developed
as a counterpart to TRIP for the circuit switched network. The attributes
and messages of CTRIP are defined. The TRIP protocol is extended with some
new optional attributes. Further, the process of converting routing information
between TRIP and CTRIP is defined. A new network element named numbering
gateway is introduced. To some extent, the ENUM directory is integrated
into the solution. Finally, some applications and scenarios based on the
solution are discussed.
Keywords: Routing, Routing protocol, Number portability, TRIP,
CTRIP, ENUM, NP, VoIP
Ignacio González Olías, Security and Auto-configuration of
Location Servers for IP Telephony, Espoo 2002
IP networks were designed to provide an effient and robust mechanism for
transferring data between remote computers. Initially, the information
exchanged was mostly computer related data: text documents, files, web
content, etc. However, the increasing popularity of this kind of networks
is encouraging the development of new services and applications that take
advantage of the existing infrastructures.
One of the emerging applications is IP telephony,
a new service aimed to allow end users to complete voice calls over IP
networks. This a clear example of how a service that was traditionally
offered using a different technology, i.e. public switched telephone networks
(PSTN), has been adapted to the IP networks.
Since the migration from one approach to another
can not take place overnight, both technologies will be interacting for
a period of time. This interaction generates new interoperability problems
that must be addressed. Data and signalling conversion between both networks
is performed by special entities called gateways.
We focus our study on the architecture that solves
the problem of gateway location. The Telephony Routing over IP (TRIP) protocol
is responsible for distributing gateway availability information between
different administrative domains, while the Server Cache Synchronization
Protocol (SCSP) performs the required database replication.
This document presents security and auto-configuration
modules for the TRIP/SCSP architecture. The former is aimed to ensure that
the data exchange takes place in a secure way, while the latter improves
the scalability, reliability and availability of the system.
We also include some test results to show how the
addition of security services to protect SCSP traffic affects the performance
of the protocol.
Keywords: interoperability, gateway location, TRIP, SCSP,
replication, security, auto-configuration.
Antti Paju, Number Portability in Interconnected Circuit and Packet Seitched
Networks, Espoo 2002
Number portability is quite a topical issue in several countries including
Finland. In Finland the communications regulatory authority (FICORA) has
ordered the GSM numbers to be portable from an operator to another from
1st of July 2003 onwards. As VoIP (Voice over IP) is getting more common,
a need arises to port subscribers from the SCN to the IP network so that
a ported-out subscriber can still keep his/her number. For a customer,
the technological transition is not any reason to change his/her telephone
number. Number portability enhances competition in the telecom markets
and improves customer satisfaction. When a subscriber moves, his/her number
does not have to be changed. Changing the telephone number can cause e.g.
significant advertising costs to business customers. So, number portability
is very useful for both business and residential customers.
Nowadays, number portability is managed with IN
technology (Intelligent Network). IN based number portability has several
drawbacks. This thesis tries to fix them by introducing a new solution,
which still uses the existing IN technology some way. The management of
number portablility is treated as an application, which is created using
standards interfaces and definitions. This thesis rejects the approach
of routing the call into the donor's network first. The aim is, that the
call is routed directly into the network where the called party is located.
Number portability requires a number translation service, which resolves
the logical directory number into a routing number, or to be more specific
into a routing address. Interoperability requires common numbering between
the SCN and IP networks. Due to the structure of PSTN, E.164 numbering
is used in both SCN and IP networks.
The solution utilizes relational databases for efficient
database management. They provide very scalable data structures and tools
for automatic data integrity management. ODBC (Open Database Connectivity)
is selected as the access inteface to relational databases. ODBC makes
the solution portable to many commercial and non-commercial SQL databases.
As a result, we get a service, which is independent on the carrier network,
and the scalability of which knocks previous database management solutions
of number portability into a cocked hat.
Keywords: NP, SQL, ODBC, DNS, SIP, ISUP, IN, TRIP, BGP
Full papers are either in PostScript or
PDF format.
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