Contributed by Windy Zou, International Sales
Manager, TSI. Email: wzou@tsiconnections.com

The rapid worldwide expansion of the wireless subscriber base and the increase in international travel are fueling the growing demand for international roaming. This demand presents a great revenue opportunity for wireless operators.

This is particularly true for Asia Pacific, which has the largest cellular/PCS subscriber base in the world, enjoying a consistent subscriber growth rate of more than 40 percent during the last few years (46 percent in 2000¹). Even with this impressive growth rate, the wireless penetration rate was only 6 percent in 2000², indicating a huge market potential for further growth.

At the same time, the economic revival in the Asia Pacific region and globalization of the world economy have contributed to the increasing amount of international travel, both within Asia and between Asia and other continents. According to projections by the International Air Transport Association, 27 million trips will be made between Asia and Europe and 26 million between Asia and North America in 2001. Travels within Asia are even more frequent. These conditions present a potential gold mine for wireless operators at a time when acquiring and retaining home subscribers is becoming more and more costly in the competitive domestic markets.

CDMA operators, such as Hutchison Telecom, KDDI, SK Telecom, Shinsegi and Telstra, are taking the lead in tapping into these revenue opportunities by launching two-way, automatic international roaming services. Hutchison, KDDI and Shinsegi launched roaming in early 2000. SK Telecom and Telstra joined the group by launching roaming in time for the Sydney Olympics in September 2000. Some of these operators have also
offered roaming to North America.

The Asia-Pacific operators have effectively deployed these global roaming services by addressing areas that include cost-effective network configuration, signaling interoperability and unified numbering scheme, billing data clearing and settlement, and online customer management.

1) Cost-effective network configuration
Traditional wireless roaming uses SS7 "A" and "B" links for signaling transport, but this approach can be cost-prohibitive outside of North America. As an alternative, the Asia Pacific operators used a creative solution offered by TSI (formerly GTE TSI) to transport SS7 signaling over frame relay networks.

By having only one network connection to TSI, this solution provides transport SS7 signaling for ANSI-41 messages, allowing operators to offer features such as call delivery and call validation. It further reduces costs by supporting applications requiring TCP/IP protocol such as electronic data transfer for billing records.

This solution also greatly simplifies SS7 testing. Instead of testing with every roaming partner, the operators need to test only with the network hub. Some operators also opted for a two-link configuration for route diversity, redundancy and added reliability.

2) Signaling interoperability and unified numbering scheme
The operators took advantage of TSI’s International Signaling Gateway, a Signaling Control Protocol (SCP) based hub that facilitates signaling interoperability among wireless operators of different countries. It provides centralized conversion and routing services for the exchange of signaling messages between various international operators with incompatible signaling and network protocols, including various versions of ITU, C7 and ANSI SS7 networks.

The solution effectively:

• Bridges the gaps of various ANSI/IS-41 revisions, including A/B, C and D, that operators use worldwide
• Provides signaling interoperability among different switch types
• Resolves point code conflicts by directing all MIN ranges and point codes to a single point code instead of multiple points codes
• Eliminates issues related to international Temporary Location Directory Numbers (TLDNs), enabling direct international call delivery
• Converts ANSI SS7 to ITU-T C7 protocols and vice versa
• Provisions SMS routing to allow SMS termination for roaming subscribers

A unified numbering scheme is critical for international roaming. The operators used the international roaming MINs (IRMs) for roaming purposes. The IRMs are administered by the International Forum on AMPS Standards Technology (IFAST), which assigns 0XXX or 1XXX digits. The other six digits are assigned by the operators that receive them.

3) Billing data clearing and settlement
To transfer billing records among roaming partners, the operators can choose between transferring them directly to their roaming partners or using a central authorized receipt point, commonly known as a clearinghouse. The Asia Pacific operators opted for the latter because it simplified the exchange of billing data with their roaming partners by handing it off to the clearinghouse. The clearinghouse acts as a single point of contact, which streamlines the processing of roamer billing data.

The clearinghouse also provides a single source of information regarding inbound and outbound roamers, as well as calculating the operators’ financial position with respect to their roaming partners. The clearinghouse edits billing records on behalf of the operators and rejects records that are duplicated or fail to meet CIBER industry standards, helping to minimize revenue loss. To further enhance revenue assurance, the clearinghouse also performs functions such as validating billing records against roaming agreements.

The clearinghouse the operators use provides a paperless environment through Web-enabled online reporting. Flexible formats allow effective and user-friendly management and analysis of large volumes of roaming data. The daily and monthly reports feature various aspects of roaming data such as financial net positions and file rejects. Billing, finance and marketing departments use these reports for their specific purposes.

4) Online customer management
When subscribers are roaming in other countries halfway around the world, it’s a challenge to provide quality customer support, especially when they roam on other operators’ networks. The Asia Pacific operators overcame that challenge by using online, real-time troubleshooting tools to provide customer service and prevent fraud.

One TSI tool gives real-time information about roaming customer activity, including ANSI-41 messaging, which helps to streamline operations and enables troubleshooting for overseas roamers. The roaming data can also be used for analysis and performance monitoring. For example, by typing in a subscriber’s MIN/ESN, operators can instantly view all the subscriber’s validation transactions and call delivery activities for the last seven days. By enabling Visitor Location Register (VLR) clearing, the operators can initiate an online request to clear a VLR entry from a switch, allowing a valid subscriber to roam in a specific roaming partner’s market.

By effectively addressing the challenges in these four areas, the Asia Pacific operators are able to offer seamless roaming to their CDMA subscribers. During the Sydney Olympics in September 2000,Telstra used TSI’s roaming services to provide customers of Japanese and Korean operators with automatic inbound CDMA roaming across the Australia-wide CDMA network. As Shinsegi concluded, using those roaming services enables effective, limitless "connection from one to 'N'th operators."

With automatic CDMA roaming, CDMA operators are now able to give their subscribers the world.

1. Global Mobile, Volume 7, Number 22, November 22, 2000
2. See note 1