Overview
The International Roaming Signaling Converter (IRSC) application supports wireless roaming between
North American ANSI based and Global ITU-T based GSM networks by providing global title translation,
gateway screening, and MTP/TCAP protocol conversion between ANSI and ITU-T networks. The
MicroLegend
TM
IRSC was released in 1996, at which time it was the first and only such system in the
world. Today, over 100 GSM operators worldwide depend on the IRSC for international GSM roaming.
Benefits
Manages all of the complexity of the GSM message interworking.
The conversion of GSM messages between ITU-T and ANSI networks is a very complex challenge. The
product performs this conversion by matching incoming ANSI and ITU SS7 messages with provisioned
information stored in each of two systems.
Powerful SS7 message manipulation.
In addition to the interworking of the ANSI and ITU-T messages, the MicroLegend
TM
IRSC can modify the
Global Title Address by adding or deleting digits. The system can also perform subsystem number
modification at the SCCP level.
Sophisticated Global Title Translation.
The MicroLegend
TM
IRSC can perform full or partial Global Title Translation (GTT) to determine the proper
routing of each SS7 message.
Advanced message routing.
Both point code and subsystem number route management are supported. Primary and secondary
destinations can be specified to enable the message routing to succeed even if a node or link becomes
unavailable.
Usage measurements.
The MicroLegend
TM
IRSC provides detailed usage measurements which can be used to drive customer
billing systems.
Mated pair configuration, with automatic re-routing of message traffic.
The IRSC is deployed in a mated pair configuration, with each link fully redundant. Each device is
capable of handling the full load of message traffic, ensuring reliable operation of the system as a whole.
Proven SS7 interface for both ANSI and ITU-T networks.
The IRSC is built on the MicroLegend
TM
Signaling Platform which has been deployed in numerous
configurations in networks all over the world, including the United States, Canada, Brazil and China.
Scalable to over seventy SS7 links.
The MicroLegend
TM
Signaling Platform, with its distributed processor architecture, enables the IRSC to
scale up smoothly as the volume of SS7 message traffic increases. From the cost-effective three slot
version to the fully-loaded twenty slot version, the MicroLegend
TM
Platform offers a full range of configu-
rations.
NEBS compatible equipment.
The MicroLegend
TM
Platform has been designed for NEBS compatibility. All of the strenuous NEBS
requirements, including electrical, physical and mechanical issues, were incorporated into the design.
MicroLegend Protocol Converters
International Roaming
Signaling Converter
Today, over
100 GSM
operators
worldwide
depend on
the
MicroLegend
IRSC for
international
roaming.
Example of an IRSC configuration
Comprehensive 7 x 24 support package.
Support is provided directly by the engineering team that developed the platform and the application.
Using a direct dial-in connection, PTIs technical support staff can perform system diagnosis and soft-
ware updating with maximum efficiency.
Functional Description
The MicroLegend
TM
IRSC supports wireless roaming between North American ANSI based and Global
ITU-T based GSM networks by providing protocol conversion on both the MTP and TCAP levels of the
SS7 stack, as well as global title translation and gateway screening services.
The IRSC application performs this conversion by matching incoming ANSI and ITU SS7 messages with
provisioned information stored in each of the two MicroLegend
TM
Signaling Platforms.
The IRSCs operate as a redundant pair, installed in two different central office locations. Each IRSC acts
independently of its mate, but contains the same operational parameters and behaves identically. In the
event of a failure of a linkset or an entire IRSC, the STPs will route gateway traffic to the available sys-
tem.
Each IRSC runs both an ANSI protocol stack and an ITU stack simultaneously. Each stack possesses a
unique individual point code. In addition to the individual point code, a virtual, or alias, point code is
shared by both IRSCs on the ITU and ANSI networks.
The IRSC contains service provisioning information, which defines how the protocol converter handles
each message thats received. The provisioning data allows the system administrators to control :
The incoming messages which will be accepted for protocol conversion based on the combination of
Called and Calling Party Number.
The Destination Point Code (DPC) of the converted message (either routed directly to the target carrier
network, or routed to an alternate, intermediary network, based on the combination of Called and
Calling Party Number). As well, secondary DPCs may be specified to provide a redundant path to both
the target network and the alternate network.
The Called Party Number digits and SCCP data required in the converted message.
The service provisioning data is
contained in the Conversion Data
table and the Screening and Re-
routing table. These are two au-
tonomous tables within the IRSC.
Individual records within the Con-
version Data Table are indexed by a
range of Called or Calling Party
Number, using 4 to 7 digits. This
range of Called or Calling Party
Numbers is associated with a Virtual
Point Code (VPC), which typically
will identify a particular end carrier
network.
When an SCCP message is received by the IRSC, the Conversion Data Table is used to identify the
VPC associated with both the Called and Calling Party Numbers. These Virtual Point Codes are then
used to lookup the appropriate record in the Screening & Rerouting Table. This table identifies the action
to take for the received message:
screen the message;
route the message normally;
route the message to the alternate network.
The
International
Roaming
Signaling
Converter
application
supports
wireless
roaming
between
North
American and
other GSM
networks.
www
.pt.com
IRSC System Architecture
The core of the IRSC system is comprised of the ANSI and ITU Stacks, along with the protocol conver-
sion application. The product includes several facilities which support the provisioning and management
of the system.
The IRSC is configured to automatically start the necessary processes to maintain the SS7 network
connections, perform protocol conversion, accept new provisioning data, generate usage measurements,
and produce log and alarm data when necessary.
Service data which describes the nature of the protocol conversion to be performed is stored perma-
nently on hard disk in the IRSC database, and dynamically in memory for real-time access by the
conversion process. The database is also manipulated by a Service Order Interface (SOI) which is run
from the local IRSC terminal. The SOI allows the user to browse, add, delete, and modify the service
data, as well as apply any changes to the active image of the database, which exists in memory. An
interface to automated service provisioning systems can also be provided. Service provisioning data is
validated and added to the IRSC database. Any errors encountered by the IRSC with the downloaded
data are reported to a locally stored status-file to be inspected and addressed by a system administrator.
Traffic (Usage or Billing) information generated by the converter is stored locally as binary data in
timestamped files for the most recent 20 days. These files are generated at intervals of 5 to 60 minutes,
depending on the data in the IRSC configuration file. The billing data can be retrieved periodically by a
downstream billing database.
The log and alarm information is stored locally as ASCII data in timestamped files for the most recent 20
days. Log and alarm information can also be transmitted from the IRSC to the network maintenance
facilities, in real-time via TCP/IP socket interface over a corporate network.
Management of the SS7 MTP Stacks is provided by a user interface run from the local IRSC terminal.
The interface allows the user to observe the status of the links and routes used by the IRSC, and to
perform standard MTP maintenance activities such as activation, deactivation and inhibiting of links.
IRSC Service Provisioning
Provisioning of the IRSC service data can be performed locally at the IRSC terminal through a simple
user interface, or can be modified to work with a remote administration system.
The local interface to the IRSC provisioning database is called the Service Order Interface (SOI). The
SOI runs on the IRSC terminal. It provides the capability to step through the database; to add, delete and
modify service data entries; and to activate the changes or quit without affecting the actual service data
used by the conversion process. The data entry capability provided locally on the IRSC is characterized
by the following steps:
The IRSC administrator invokes the character-based SOI to the local provisioning database in the
IRSC. The user interface presents a working copy of the actual service data. No changes to the actual
service data takes place until the administrator explicitly activates the modifications in the working copy.
The working copy of the local database can be viewed and modified.
A command is executed to activate the working copy of the data. The administrator is provided with
notification of acceptance or rejection of the new DB
image.
Activation of the working copy of the database results in
status being returned to the user to indicate whether the
activation process was successful. If the IRSC detects
invalid data, information about the errors will be displayed
by the SOI.
2000 Performance Technologies, Inc. All rights reserved. R507200
Performance Technologies, Inc.
315 Science Parkway
Rochester, New York 14620
Tel:
716-256-0200
Fax:
716-256-0791
Email:
sales@microlegend.com
Web:
http://www.pt.com
PDF 
ZIP