What is a Global title?

A Global title (GT) is an address used in the SCCP protocol for routing signaling messages on various telecommunications networks.

Global titles are unique addresses that refer to only one destination, but in practice, those destinations can change over a given time frame.

They are crucial for routing calls, SMS messages, and other services across different networks worldwide.

GT structure is defined by the ITU-T signaling connection control part formats and codes recommendation (Q.713), further extended in the supporting numbering plan standards. Other national variants of the Signaling Connection Control Part (SCCP) define their format for the Global title. The value of a Global title is a sequence of attributes that modify the address value. The length of a Global title address is from 1 to 21 digits and works within SS7 (Signaling Number 7) for routing messages.

How does a Global title work?

Global title routes call from one network to another. When placing a call, the Global title identifies the destination network and specific location within the network. Then, the call routes through the SS7 network to the destination network, and the call is connected. It also enables services such as number portability and international roaming.

Structure of a Global title

A GT isn’t just a random string of numbers, it has a specific structure:

  • Country code: Identifies the originating country.
  • Network identification code: Specifies the network within the country.
  • Subsystem number (SSN): Pinpoints a specific application or service on the network.
  • Translation type (sometimes): Indicates a specific type of routing or translation needed.

Why Global titles are important?

GTs are the backbone of efficient call routing across different networks. Without them, it would be challenging for networks to locate specific users, hindering calls from connecting across carriers both domestically and internationally.

When traveling internationally, your phone is essentially a guest on another network. Global titles allow networks worldwide to identify you and route calls, SMS, and data services as if you were still within your home network.

Next, number portability, the ability to keep your phone number when switching carriers, heavily relies on Global titles. GTs help ensure that calls and messages still reach you on your new network since the GT can be updated to point to your new carrier’s network.

Many businesses use SMS services for things like two-factor authentication, appointment reminders, and other notifications. Global titles are essential in ensuring these SMS messages reach the intended users, even if the users are on different networks.

While GTs can be misused, they also play a role in some fraud prevention systems. By analyzing GT patterns, networks can detect suspicious activity and potentially block fraudulent calls or messages.

Global title analysis

The primary purpose of Global title analysis (GTA) is to determine the correct routing path for a signaling message based on its destination Global title. This involves:

  • Decoding the Global title: The GTA process examines the structure of the Global title to extract information like country codes, numbering plans, and the specific destination address.
  • Lookup and translation: It looks up this information in databases or routing tables to determine how to route the message correctly. The Global title may be translated into another format or a specific Point code for the destination node within the network.

GTA typically occurs at network elements responsible for routing SS7 messages. This often includes:

  • Signaling transfer points (STPs): Core nodes that route SS7 messages across the network.
  • Service control points (SCPs): Specialized nodes that provide services like number portability and routing databases

Global title analysis can be computationally intensive, especially in large networks. To optimize performance, systems often use:

  • Tree-based structures: Organizing routing information in tree-like structures enables efficient lookups.
  • Caching: Caching is frequently used results to reduce the need for repeated database lookups.

What is Global title leasing?

Global title Leasing is a practice where service providers lease access to Global titles and Hosts to businesses.

This lets the service provider route messages through the SS7 network without having to own their own GTs directly. It provides a faster way for these service providers to establish connectivity and offer services like SMS, voice, or roaming to their customers.

Smaller companies or those specializing in specific services (like A2P SMS) can use GT leasing to offer these services globally without investing in the complex infrastructure required to own their own GTs. Meanwhile, MNOs can generate revenue by leasing out spare GT capacity.

Leased GTs can potentially be used for illegal or fraudulent purposes, tarnishing the reputation of the original MNO that owns the GT. Depending on the specific setup, sensitive location or subscriber data might be exposed or shared.

Operators should have strict contracts and vetting processes to ensure lessees use their GTs responsibly.

Use cases

  • A2P SMS: Application-to-Person messaging services often use GT leasing for global SMS delivery.
  • Sponsored roaming: Allowing customers to roam in other countries without buying a dedicated local SIM.
  • Fraud detection: Using location information associated with GTs to help detect and prevent fraudulent calls or messages.

What is a Virtual Global title?

A Virtual Global title (VGT) is a concept that adds another layer of flexibility to the addressing and routing of messages in telecom networks.

A VGT allows a single GT to represent multiple physical destinations for a service. Incoming calls or messages addressed to a VGT can be distributed across various physical nodes, improving load sharing and reducing the possibility of a single point of failure. With a VGT, network operators can migrate services between nodes by changing the mapping between the VGT and the physical point codes. This can be done transparently to the rest of the network, minimizing disruptions.

Virtual Global titles are usually implemented in specialized network elements or databases that perform advanced routing functions. These elements can:

  1. Recognize a VGT: Identify an incoming message is addressed to a Virtual Global title.
  2. Translate and route dynamically: Translate the VGT into an appropriate point code based on factors like load distribution policies, service availability, or other criteria. This real-time decision-making enables the flexibility of a VGT.

What is Global title translation?

Global title translation (GTT) is the process within telecommunication networks that converts a GT into specific routing instructions. A GT is a unique address used in the SS7 protocol to identify destinations for calls and messages. GTT essentially translates this generic address into the language the specific network understands, ensuring messages reach their intended recipients.

What is MAP Global title faking?

MAP Global title faking is when messages are manipulated by the sending party changing a MAP parameter, by changing the originator to prevent detection by a firewall, or by pretending to be a mobile operator without a commercial agreement with the sender.

What is SCCP Global title faking?

SCCP Global title faking is sending a message to a handset originating from a Global title that either does not belong to the sender or has been leased from a third party and where the SCCP or MAP addresses are manipulated.

What is the difference between a Point code and a Global title?

A Point code is a numeric address that uniquely identifies a specific node (like a switch or signaling point) within the SS7 telecommunications network.

Networks directly connected to a particular node will have their Point code hardcoded in their routing information. Remote networks might not have specific Point codes for every possible destination.

How do they work together?

  1. Message routing: When a message needs to be routed, it often includes a destination Global title.
  2. Global title translation (GTT): Specialized network elements or databases perform GTT. This is where the Global title is translated into the appropriate Point code for the specific node where the destination resides.
  3. Routing to the node: Once the Point code is determined, the signaling message is routed to the correct physical node in the network.

Global titles make routing across complex networks more efficient and flexible, while a Point code represents the fixed address of a single network element.


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May 10th, 2024
6 min read