DTMF Tone Scheduling During Ring Pause Periods
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Solution Overview
Problem
Mobile devices face challenges in reliably detecting Dual Tone MultiFrequency (DTMF) tones over a voice channel while producing a ring progress tone, and often lack access to an active data communication path for status and control updates in enterprise communication systems.
Innovation Solution
The system schedules DTMF tones to be transmitted over a voice channel during pause periods of a cyclic ring tone pattern, ensuring they are more likely to be detected by the mobile device, by estimating the network and processing delays and rescheduling transmissions accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DTMF tones are transmitted over a voice channel during ring periods, then status and control information can be updated, but the mobile device cannot reliably detect the tones while producing a ring progress tone
Solution Approach 1:
The system utilizes the periodic structure of the ring tone (alternating ring periods and pause periods) to transmit DTMF tones only during pause periods when the mobile device is not producing a ring progress tone. This periodic scheduling ensures that control tones are transmitted during windows of opportunity when the device's own ring tone is not interfering with detection.
Solution Approach 2:
The server estimates network and processing delays in advance to predict when pause periods will occur at the mobile device. By calculating the round-trip delay and scheduling DTMF tone transmission proactively during predicted pause periods, the system ensures tones arrive during optimal detection windows before the device resumes producing its ring tone.
2Adaptability or versatility
If DTMF tones are transmitted during ring periods, then communication can occur without data channels, but tone detection fails due to device producing ring tone
Solution Approach 1:
The solution maintains the adaptability of using voice channels for control communication by scheduling DTMF transmissions during pause periods of the ring cycle. This periodic transmission strategy enables communication without data channels while avoiding the reliability issue of tone detection during active ring periods.
Solution Approach 2:
The system converts the harmful interference of the ring progress tone into a useful scheduling signal. The presence and periodicity of the ring tone create defined pause periods that serve as optimal transmission windows, transforming the interference problem into a structured opportunity for reliable tone transmission.
3Reliability
If network and processing delays are not estimated, then transmission scheduling is simple, but DTMF tones arrive at wrong times and are not detected
Solution Approach 1:
The server performs preliminary estimation of network transmission delay and device processing delay to predict future pause period timing. By calculating these delays in advance and using them to proactively schedule DTMF tone transmissions, the system ensures tones arrive during optimal detection windows without requiring complex real-time synchronization.
Solution Approach 2:
The system uses feedback from observed ring tone patterns and timing information to refine delay estimates and improve scheduling accuracy. By monitoring the actual timing of ring periods and adjusting predictions accordingly, the system maintains reliable tone delivery while managing scheduling complexity through adaptive learning.
Data Source
AI summary
A computer implemented method for transmitting dual tone multi-frequency (DTMF) tones is disclosed. The method includes sending an indication to a mobile device to start a cyclic ring tone including ring and pause periods. The delay incurred to send a DTMF tone to the mobile device is estimated. The server schedules the transmission of the DTMF tone to be received at the mobile device during a pause period of the cyclic ring tone and the DTMF tone is sent as scheduled.