From Data to API: A Complete Practice for Building an End-to-End Telecom Customer Churn Prediction System

This article introduces an open-source telecom customer churn prediction project, covering the end-to-end workflow from data exploration, feature engineering, model training to FastAPI deployment. It demonstrates how to use machine learning to solve customer retention business problems, helping enterprises identify high-risk churn customers in advance and take retention measures.

The cost of acquiring new customers is 5-7 times that of retaining existing ones, and customer churn in the telecom industry directly affects revenue. The goal of this project is to build a complete machine learning system from raw data to deployment as a REST API, identifying high-risk customers who may churn and providing support for business decisions. The project uses the IBM Kaggle Telecom Customer Dataset (7043 records, 20 features, 26.5% churn rate).

1. Data Preprocessing: Fix the data type issue of the TotalCharges field and remove new customers with insufficient historical data;
2. Feature Engineering: Delete the redundant feature TotalCharges, one-hot encode categorical features, and build the num_services feature to count the number of subscribed services;
3. Model Selection: Compare Logistic Regression (ROC-AUC 0.849), Gradient Boosting (0.847), Random Forest (0.825), and finally select Gradient Boosting;
4. Tuning: Determine optimal parameters (learning rate 0.05, max depth 3, etc.) via GridSearchCV.

• Test Set Performance: ROC-AUC reaches 0.842, with good discrimination ability;
• Threshold Tuning: Lower the threshold to 0.3, recall rate increases to 79% (fewer missed detections), which meets the business requirement of "better to misjudge than to miss";
• Feature Importance: Tenure, fiber optic service, electronic check payment, contract type, and monthly consumption amount are key churn drivers, consistent with the conclusions from data exploration.

Use FastAPI to encapsulate the model into a REST API, providing health check and prediction endpoints. The caller only needs to provide raw data. Application scenarios include: real-time customer scoring (CRM automatically obtains risk scores), batch prediction (generating high-risk customer lists monthly), product optimization decision support (improving services based on feature importance), and customer lifecycle management (early intervention at key nodes).

Highlights: End-to-end completeness, business-oriented modeling, reproducibility, concise and effective design; Expansion Ideas: Try XGBoost/LightGBM and deep learning models; add model monitoring and A/B testing frameworks; combine customer value stratification management, develop personalized retention strategies, and establish churn attribution analysis.