기본 안드로이드 서비스 구조

1. Core System services
- Activity manager (manages application lifecycle)
- Package manager (loads apk files)
- Window manager (handles applications window manager interaction with surface flinger)
- Resource manager (handles media resources)
- Content providers (provides data to application)
- View system (provides widgets, views, layouts to applications)

2. Hardware services
- Provides low-level access to hardware device
- Location manager
- Telephony manager
- Bluetooth service
- WiFi service
- USB service
- Sensor service

http://www.linuxjournal.com/magazine/java-api-androids-telephony-stack?page=0,4&quicktabs_1=2

http://sites.google.com/site/io/inside-the-android-application-framework

http://www.netmite.com/android/mydroid/development/pdk/docs/telephony.html