-- README for frameworks/opt/telephony -- This directory contains telephony libraries which function as the implementation code for APIs in TelephonyManager, SubscriptionManager, SmsManager and others. These libraries run in the com.android.phone process and exist to support telephony services created by the user’s apps (generally carrier apps), or by the system. This includes making phone calls, sending SMS/MMS, and connecting to data. Many APIs are plumbed down to the radio through HIDL calls defined in hardware/interfaces/radio/ hardware/interfaces/radio/config and return values that are sent back up as responses. We define several AIDL interfaces in frameworks/base/telephony/ which we implement in this directory and packages/services/Telephony. This IPC scheme allows us to run public API code in the calling process, while the telephony-related code runs in the privileged com.android.phone process. Such implementations include PhoneInterfaceManager, SubscriptionManagerService and others. The declaration of the com.android.phone process is in packages/services/telephony and the top-level application class is PhoneApp, which initializes everything else. -- Testing -- Unit tests are found in frameworks/opt/telephony/tests and can be run on a device connected through ADB with the command: atest FrameworksTelephonyTests Tests can also be run individually or by class: atest <testClassName atest <testClassName>#<testMethodName> For more on atest run `atest --help`