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The Importance of SS7 Stack in Mobile Networks

This article comprehensively summarizes the SS7 stack's significance in mobile networks, including its architecture and diverse range of services.

The use of mobile networks has become a fundamental aspect of our day-to-day routines, facilitating constant access to communication and information. A crucial element of mobile networks is the Signaling System 7 (SS7) protocol stack, which plays a vital role in delivering essential functions such as call routing, SMS messaging, network management, security, interconnectivity, and protocol evolution. This article comprehensively summarizes the SS7 stack's significance in mobile networks, including its architecture and diverse range of services.

Core Network Functionality

The SS7 protocol stack is a vital component of mobile networks. It consists of multiple layers that perform specific functions essential to the smooth operation of mobile networks. Call routing, SMS messaging, roaming, network management, security, value-added services, interconnectivity, protocol evolution, and customer experience are some of the critical functionalities of the SS7 protocol stack. The SS7 protocol suite is continually evolving, ensuring optimal performance, security, and backward compatibility. It plays a crucial role in providing various services to subscribers and enhancing their experience while minimizing service disruptions.

Call Routing

The SS7 protocol stack's call routing feature is of utmost importance as it allows mobile networks to initiate and sustain communication sessions between different network entities. Call routing involves several stages, including location routing, which identifies the subscriber's current location, and call routing, which identifies the optimal route for the call to connect to its intended recipient.

Network capacity is a pivotal aspect of call routing, as it determines the volume of traffic that a network can accommodate at a given moment. Several factors influence network capacity, such as the number of subscribers, the type of mobile services offered, and the network's geographical coverage. Additionally, network capacity plays a crucial role in determining the level of quality of service (QoS) that subscribers can expect, encompassing aspects such as call quality, data transfer speed, and service availability.

The call routing process is also influenced by subscriber preferences, enabling them to personalize their call routing options to suit their individual requirements. Subscribers can block incoming calls from certain numbers or permit only specific numbers to reach them. These preferences are stored in the HLR and are regularly updated to ensure that the subscriber's call routing options reflect their current needs.

SMS Messaging

SMS messaging is one of the critical functionalities of the SS7 protocol stack, enabling mobile subscribers to send and receive text messages quickly and reliably. The SS7 signaling network utilizes signaling messages to establish and maintain SMS sessions between network entities, ensuring prompt and reliable message delivery.

The SMS messaging process comprises two types of messages: Mobile-Terminated (MT) SMS and Mobile-Originated (MO) SMS. MT SMS conveys messages from the network to the subscriber, whereas MO SMS delivers messages from the subscriber to the network. When a subscriber initiates an MO SMS, the message is first transmitted to the nearest base station, which then relays it to the Mobile Switching Center (MSC). The MSC then sends a signaling message to the Short Message Service Center (SMSC) requesting that the message be delivered to the intended recipient. The SMSC then transfers the message to the recipient's network, where it is finally received on the recipient's mobile device.

The SS7 protocol stack also supports multimedia messaging (MMS), allowing subscribers to send and receive multimedia content such as images, videos, and audio files. MMS messages require more bandwidth than SMS messages, as they can include multimedia content, which can affect the message delivery time.

The SS7 protocol stack also supports SMS over IP, enabling subscribers to send and receive SMS messages over an IP-based network like the Internet. 

Aside from its core functionalities, the SS7 protocol stack also provides numerous value-added services that enrich the SMS messaging experience for subscribers. Among these services is premium messaging, which allows subscribers to receive and send premium SMS messages containing customized content like weather alerts, news updates, and other personalized messages.


Roaming is a vital feature of mobile networks, enabling subscribers to access services seamlessly while outside their home network. The SS7 protocol stack plays a crucial role in ensuring efficient roaming by utilizing signaling messages to establish and maintain connections between network entities, enabling subscribers to access services in a foreign network.

One important aspect of roaming is location updating. Location updating involves updating the subscriber's location information in the network, ensuring that the network knows where the subscriber is located. 

Roaming also involves billing and charging. Billing and charging ensure that subscribers are charged appropriately for the services they use while roaming. The SS7 protocol stack supports roaming charging, which involves calculating the charges for roaming services and updating the subscriber's account accordingly.

Roaming also involves security. Roaming can be a security risk, as subscribers may be vulnerable to attacks while using foreign networks. The SS7 protocol stack supports various security mechanisms, including authentication and encryption, to ensure the security of communication sessions between network entities.

Network Management

The SS7 protocol stack's network management feature is of utmost importance as it provides several management messages that enable network operators to oversee and regulate various network entities, such as mobile devices, base stations, and signaling nodes. Network management plays a pivotal role in maintaining the optimal performance of mobile networks by identifying and addressing network issues and ensuring efficient network operation.

The management messages provided by the SS7 protocol stack include messages for monitoring network performance, detecting and diagnosing faults, and configuring and controlling network entities. These messages enable network operators to monitor network traffic, detect bottlenecks and congestion, and diagnose network issues that can lead to service disruptions.

One of the critical management functionalities provided by the SS7 protocol stack is fault management. The SS7 signaling network provides various fault management messages that enable network operators to promptly detect, diagnose, and address network faults. 


The SS7 protocol stack plays a crucial role in securing mobile networks against fraudulent activities such as subscriber impersonation and SIM cloning. The SS7 signaling network utilizes signaling messages to authenticate subscribers and prevent unauthorized access to the network.

One of the security mechanisms supported by the SS7 protocol stack is encryption. Encryption is the process of converting plain text into ciphertext to prevent unauthorized access to sensitive information. 

Another security mechanism supported by the SS7 protocol stack is digital signatures. Digital signatures are used to verify the authenticity and integrity of messages exchanged between network entities. Digital signatures are created using public-key cryptography, where a digital signature is created by encrypting a message hash with the sender's private key. 

The SS7 protocol stack also supports message integrity checks, which ensure that messages exchanged between network entities are not modified or tampered with during transmission. Message integrity checks are implemented using various cryptographic techniques, such as Message Authentication Code (MAC) and Hash-based Message Authentication Code (HMAC).

Value-Added Services

The SS7 protocol stack goes beyond the fundamental call and SMS functions and provides value-added services that enhance the user's experience. Location-Based Services (LBS) is one such service that utilizes the subscriber's location information to offer services like navigation, location-based advertising, and emergency services based on their location.

Navigation is a popular LBS that provides subscribers with real-time directions to their desired destinations. Navigation services require the SS7 signaling network to locate the subscriber's device, determine the subscriber's destination, and calculate the best route to the destination. This involves sending signaling messages between network entities to obtain location information, such as GPS coordinates, and provide navigation instructions to the subscriber.

Location-based advertising is another LBS that utilizes the subscriber's location information to provide targeted advertisements. This type of advertising is highly effective since it is tailored to the subscriber's current location and interests. 

Emergency services are a crucial LBS that uses the SS7 signaling network, navigation, and location-based advertising to offer customers instant aid in urgent situations. These services, which also need the usage of the SS7 signaling network to detect the subscriber's device and pinpoint their location, include ambulance, fire, and police services. The emergency service provider can send the right response team to the subscriber's location to help once they get the location information.

Another value-added service enabled by the SS7 protocol stack is mobile banking. 
Mobile banking services allow subscribers to access financial services using their mobile devices, including account balance inquiries, fund transfers, and bill payments. Mobile banking requires secure communication between the subscriber's device and the financial institution's servers. 


Modern telecommunications depend on interconnectivity to maintain smooth communication between various networks. This function enables data interchange and communication between several carriers, ensuring that their subscribers always receive services no matter where they are.

Interconnectivity offers several advantages, including the ability to exchange both voice and data traffic between networks, even across international boundaries. This functionality allows customers to stay connected and use various communication services, such as making and receiving calls, sending messages, and accessing the Internet, regardless of their location globally.

In addition, interconnectivity promotes collaboration and resource-sharing among carriers, leading to enhanced network coverage, capacity, and reliability. By working together, carriers can optimize network performance and provide their customers with seamless and uninterrupted services.

Protocol Evolution

In the telecommunications industry, the development of protocols plays a vital role in improving communication services. The continuous advancement of technology has led to increasing demand for new and improved protocols that can fulfill the evolving needs of users.

One major element driving protocol change is the need for faster data transfer speeds. It is necessary to build protocols to accommodate user needs for better upload and download rates. When it comes to delivering greater data transfer speeds, lower latency, and overall improved network performance, protocols like 5G and Wi-Fi 6 are vital.

The growth of emerging technologies like the Internet of Things (IoT) and cloud computing also heavily depends on protocol advancement. The demand for protocols that can accommodate the specific needs of these technologies is increasing as they continue to gain popularity. While protocols like OpenFlow and SDN are designed to enable improved network management for cloud-based services, protocols like MQTT and CoAP are designed to provide effective and dependable communication for IoT devices.

Customer Experience

Customer experience is an essential aspect of the telecommunications industry, and companies constantly strive to provide their customers with the best possible experience. 

Telecommunication companies can enhance customer experience by providing personalized services. This entails offering tailored packages that cater to each customer's unique requirements.

Another way to improve customer experience is by offering superior customer service. Companies can also use customer feedback to identify areas for improvement and make changes accordingly.

Telecommunication companies can also improve customer experience by investing in user-friendly interfaces and self-service options. This includes designing easy-to-use mobile applications and websites that allow customers to manage their accounts, pay bills, and troubleshoot issues on their own. These interfaces can help reduce the need for customer service interactions and provide a more streamlined experience for customers.

In conclusion, the SS7 protocol stack is an essential component of mobile networks, providing critical functionalities like call routing, SMS messaging, network management, security, interconnectivity, and protocol evolution. By facilitating efficient communication among network entities, the SS7 protocol suite ensures seamless reception and transmission of calls and messages for users without interruptions. Additionally, the SS7 protocol stack enables users to access services smoothly even when they are not within their home network through seamless roaming. This protocol suite is constantly evolving to meet the changing needs of mobile networks, thereby enabling mobile network operators to offer their subscribers top-notch services.

Experience the power and reliability of Mobius SS7 for yourself. Visit our website to learn more about our SS7 solutions and how they can enhance your mobile network operations today.

May 08,2023 ● 7 min read

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