DTMF Handling During Interswitch Handover
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Solution Overview
Problem
In personal communication service systems, interswitch handovers often result in errors and service losses due to the second switching station ignoring DTMF requests before a complete voice path is established, leading to missing digits and lost supplementary services during call transfers.
Innovation Solution
The second switching station sends DTMF digits received during an interswitch handover to the first switching station, which processes and acknowledges these digits, ensuring that tones are played and services are triggered correctly, even during incomplete voice path handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the second switching station ignores DTMF requests during interswitch handover, then the voice path establishment is simplified and faster, but DTMF digits are lost and service continuity is broken
Solution Approach 1:
The second switching station sets up a message queue in advance to store DTMF requests that arrive during the handover process. This preliminary preparation ensures that even though the voice path is not fully established, DTMF digits are captured and will be processed later when the handover is complete, thus maintaining both speed and reliability.
Solution Approach 2:
The message queue acts as an intermediary mechanism between the second switching station and the first switching station. It temporarily holds DTMF requests during the handover transition and enables their successful transmission to the first switching station after the voice path is established, resolving the contradiction between fast handover and reliable DTMF handling.
2Reliability
If the second switching station processes DTMF requests before voice path is complete, then service continuity is maintained, but processing errors occur due to incomplete call information
Solution Approach 1:
The second switching station preliminarily captures and stores DTMF requests in a message queue during the handover process, before the voice path is fully established. This ensures service continuity by preserving the requests for later processing when call information is complete, avoiding processing errors while maintaining continuity.
Solution Approach 2:
The system uses feedback mechanisms where the second switching station sends stored DTMF requests to the first switching station after the handover is complete. This feedback loop ensures that DTMF processing occurs with full call information available, eliminating errors while maintaining service continuity throughout the handover process.
3Reliability
If DTMF requests are stored and transmitted to the first switching station, then service continuity is maintained, but system complexity increases
Solution Approach 1:
The second switching station sets up a message queue in advance to handle DTMF requests during handover. This preliminary action simplifies the overall process by providing a straightforward store-and-forward mechanism, avoiding complex real-time coordination while maintaining service continuity.
Solution Approach 2:
The message queue serves as a simple intermediary that bridges the second switching station and the first switching station during handover. It provides a straightforward mechanism for transferring DTMF requests, maintaining service continuity without introducing significant system complexity through its simple queue-based approach.
Data Source
AI summary
In an embodiment of the method for handling subscriber input during interswitch handover of a call from a first switching station to a second switching station, DTMF digits received at the second switching station are sent in a message to the first switching station. The first switching station then performs an operation on the received digits such as playing the DTMF tones to a network or triggering a service.