This document discusses phone calls on Android. It describes the radio interface layer (RIL) that provides an abstraction layer between the Android telephony service and radio hardware. The RIL includes a RIL daemon and vendor RIL. The RIL daemon initializes the vendor RIL and processes communication from Android services, dispatching calls to the vendor RIL. The vendor RIL then processes communication with the radio hardware.

1. Android –
Phone Calls
Yong Heui Cho @ Mokwon University
Some of slides are referred to:
[1] Android Radio Layer Interface, slideshare.

2. 2
Smart Device Structure
5. Android – Message
6. Android – BroadcastReceiver
7. Android – Phone Calls
8. Introduction to IoT

3. 3
android.telephony

4. 4
Radio Interface Layer
• RIL
– Abstraction layer between Android
telephony service and radio HW
– Components: RIL daemon, vendor RIL
solicited unsolicited

5. 5
□ Courtesy to Android Radio Layer Interface, slideshare.
Android RIL stack

6. 6
RIL Components
• RIL daemon
– The RIL daemon initializes the vendor RIL,
processes all communication from Android
telephony services, and dispatches calls to the
vendor RIL as solicited commands.
• Vendor RIL
– The radio-specific Vendor RIL of ril.h that
processes all communication with radio HW and
dispatches calls to the RIL daemon (rild) through
unsolicited commands.

7. 7
RILD Internal Structure