Telecom Customer Data Schema

erDiagram
  CUSTOMER ||--o{ ACCOUNT : owns
  ACCOUNT ||--o{ SUBSCRIPTION : has
  SUBSCRIPTION ||--|| SIM : uses
  PLAN ||--o{ SUBSCRIPTION : "subscribed to"
  ACCOUNT ||--o{ BILL : "billed as"
  BILL ||--|{ BILL_LINE : contains
  CUSTOMER {
    int id PK
    string name
    string kyc_status
  }
  ACCOUNT {
    int id PK
    int customer_id FK
    string type
  }
  SUBSCRIPTION {
    int id PK
    int account_id FK
    string msisdn
    int plan_id FK
    string status
  }
  SIM {
    string iccid PK
    int subscription_id FK
    string imsi
  }
  PLAN {
    int id PK
    string name
    decimal price
    int data_gb
  }