As a product manager of a video calling app, success can be measured in various ways depending on the goals of the company. Here are some metrics that I would consider: 1. User adoption and retention: The number of users who download and use the app, as well as the frequency and duration of their use, can indicate whether the app is meeting their needs and providing a satisfactory experience. 2. Quality of service: Technical metrics such as latency, call quality, and uptime can be used to measure the reliability and overall quality of the app. 3. Feature usage: Tracking which features are being used most frequently can help identify which features are most valuable to users and which ones may need further development. 4. Customer satisfaction: Collecting feedback from users through surveys, ratings, and reviews can provide insight into their overall satisfaction with the app and what improvements they would like to see. 5. Revenue: If the goal of the company is to generate revenue, then metrics such as the number of paid subscriptions, in-app purchases, and advertising revenue can be used to track the app's financial success. Ultimately, the success of a video calling app should be measured by its ability to meet the needs and expectations of its users while also achieving the goals of the company. It's important to regularly review and adjust these metrics to ensure that the app is continuously improving and meeting the evolving needs of its users.