As a retrieval system, based on the following information:

Time: March 2023, query volume: call duration, data: the call duration in March 2023 is 245. Time: April 2023, query volume: number of calls, data: the number of calls in April 2023 is 987.
Time: April 2023, query volume: call duration, data: the call duration in April 2023 is 765.

Please answer the question concisely: cumulative call duration in March Write your response with exactly 7 paragraphs, separated with the markdown divider: ***.
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