What is SSP Service Switching Point

Service Switching Point (SSP) Explained Technically

In telecommunication networks, a Service Switching Point (SSP) is a crucial element responsible for call processing and control within the Intelligent Network (IN) architecture. It acts as the initial point of contact for a call placed by a user and handles various tasks to establish and manage the connection. Here's a breakdown of the key technical aspects of SSP:

Functionality:

• Call Initiation and Routing: When a user dials a number, the call request is first directed to the SSP associated with their phone line. The SSP analyzes the dialed digits and performs:
  • Address Analysis: Determines the type of number dialed (e.g., local, long-distance, mobile) and identifies the destination network.
  • Routing Selection: Based on routing tables and databases, the SSP selects the most appropriate path for connecting the call to the destination. Factors like cost, quality, and network availability are considered.
• Call Setup and Control: After selecting the routing path, the SSP initiates the call setup process. It communicates with other network elements (e.g., Signaling Gateways, Service Control Points) to establish the connection and exchange signaling information. This involves:
  • Sending call setup messages to the destination network.
  • Negotiating call parameters like bandwidth and service type.
  • Handling call features like call forwarding, call waiting, and conferencing.
• Interaction with Service Control Points (SCPs): In the IN architecture, SCPs house service logic and control data. The SSP communicates with SCPs to determine how to handle specific call types or features. For example, the SSP might query an SCP to determine the appropriate routing for a toll-free number.
• Connection Management: The SSP monitors the call throughout its duration, handling events like call termination, call holds, and transfers.

Technical Implementation:

• SSPs are typically implemented as software applications running on dedicated telephony hardware. They utilize various protocols for communication with other network elements:
  • Signaling System No. 7 (SS7): For exchanging call control information with other network elements.
  • MTP (Message Transfer Part): For reliable and sequenced message delivery within SS7.
  • Other application-specific protocols: Depending on the specific services offered, additional protocols might be used for communication with SCPs or other network components.

Benefits of using SSPs:

• Enhanced Call Processing Capabilities: The separation of call control and service logic (handled by SCPs) allows for greater flexibility and scalability in handling different call types and features.
• Efficient Network Resource Management: By performing intelligent routing based on call characteristics and network conditions, SSPs optimize network resource utilization.
• Improved Service Delivery: SSPs facilitate the implementation of advanced call features and services, enhancing the overall user experience.

Understanding SSPs is essential for anyone involved in the design, operation, and maintenance of telecommunication networks.

Additional Considerations:

• With the emergence of next-generation communication technologies like Voice over IP (VoIP), the role of traditional SSPs might evolve. However, the core principles of call control and service logic separation remain relevant in modern network architectures.