What is SS7 signaling system 7

SS7: Signaling System No. 7 Explained Technically

Signaling System No. 7 (SS7), also known as Common Channel Signaling System 7 (CCSS-7) in North America, is a set of telephony signaling protocols used for setting up and tearing down telephone calls and other telecommunication services. It operates on a dedicated network separate from the voice channels, allowing for faster and more efficient call setup compared to in-band signaling used in older systems.

Here's a breakdown of the key aspects of SS7:

Components:

• Signaling Points: Network elements that generate and receive signaling messages. These can be Service Switching Points (SSPs) like telephone switches, Signal Transfer Points (STPs) that route messages between SSPs, and Service Control Points (SCPs) that manage databases for services like call routing and subscriber information.
• Signaling Links: Dedicated communication channels that carry SS7 messages between signaling points. These links can be of various types (A, B, C, D, E, and F) with different characteristics.
• Signaling Messages: Structured messages containing information about call setup, call progress, call termination, and other telephony services. These messages follow specific protocols defined by SS7 standards.

Benefits of SS7:

• Faster Call Setup: Compared to in-band signaling where call setup information is carried within the voice channel, SS7 utilizes dedicated signaling links for faster call establishment.
• Enhanced Services: SS7 enables various advanced services like call forwarding, call waiting, caller ID, and mobile number portability by providing a dedicated signaling channel for managing these features.
• Improved Network Efficiency: By separating signaling from voice traffic, SS7 allows for more efficient utilization of voice channels and network resources.
• Scalability: The SS7 architecture can be easily scaled to accommodate growing network demands.

How SS7 Works:

1. Call Initiation: When a user dials a phone number, the originating SSP sends a call setup message through the SS7 network to the destination SSP.
2. Routing and Verification: The message includes information like dialed digits and calling party information. The message travels through STPs, which route it based on routing tables and network configuration. The destination SSP might also communicate with SCPs to verify subscriber information or access call routing data.
3. Call Establishment: If the call can be completed, the destination SSP sends an "alerting" message back to the originating SSP, notifying them that the called party is ringing. Upon receiving an answer signal, the connection is established, and voice communication can begin.
4. Call Termination: When a call is ended, either party sends a call disconnect message through the SS7 network, and the connection is terminated.

Security Considerations:

• While SS7 offers numerous benefits, it's important to acknowledge potential security concerns. The SS7 protocol was not originally designed with robust security measures, and vulnerabilities might exist.
• Measures like message authentication and encryption are being implemented to improve the security of SS7 networks.

Evolution and Future of SS7:

• Although newer protocols like Diameter are emerging for specific applications, SS7 remains a critical part of global telecommunication infrastructure.
• Ongoing efforts focus on improving the security and efficiency of SS7 to address evolving communication needs.

Conclusion:

SS7 has played a significant role in the development of modern telecommunication networks. Understanding its technical details and functionalities provides valuable insight into how call setup, service management, and overall network efficiency are achieved in today's communication systems.