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Telephony API

Telephony provides cellular communication capabilities. framework/telephony is the interface layer that openvela exposes to the application layer for cellular communication, also known as TAPI (Telephony API). The encapsulated interfaces cover cellular communication services: network services, calls, SMS, data, SIM dual-card, and modem configuration management.

TAPI is independent of the openvela telephony core stack. Its internal logic uses DBUS LIB to encapsulate the business logic of the Core Stack, shielding the complexity of D-Bus operations. It provides standardized and unified Telephony API interface definitions in standard C, making it convenient for openvela application layer APPs to use and enabling reuse across openvela system versions.

openvela Implementation Notes

• Architecture: TAPI encapsulates the Telephony Core Stack (oFono) via D-Bus, exposing standard C interfaces externally
• SIM identification: Different SIM slots are distinguished via the slot_id parameter
• Asynchronous model: Most operations return results asynchronously through callback functions

Module Overview

Module	Source	API Documentation	Description
Unified header file	tapi.h	Common Utilities	Common type definitions, string/enum conversion utils
Radio interface	tapi_manager.c/h	Manager	Telephony initialization, status query, event registration
Call interface	tapi_call.c/h	Call	Voice call control
Supplementary Services	tapi_ss.c/h	Supplementary Services (SS)	Call forwarding/barring/waiting/CLIR/USSD
Simplified Phone Service	tapi_phone.c/h	Simplified Phone Service	Lightweight client wrapper
Network interface	tapi_network.c/h	Network	Network registration, signal, operator
Data interface	tapi_data.c/h	Data	Cellular data connection
SIM interface	tapi_sim.c/h	SIM Card	SIM card management
SIM Toolkit	tapi_stk.c/h	SIM Toolkit	STK Agent and SIM proactive commands
Phonebook	tapi_phonebook.c/h	Phonebook	ADN/FDN phonebook management
SMS interface	tapi_sms.c/h	SMS	SMS message sending and receiving
Cell Broadcast	tapi_cbs.c/h	Cell Broadcast (CBS)	Cell broadcast messages
IMS interface	tapi_ims.c/h	IMS	VoLTE/VoWiFi

TAPI Configuration

A complete Telephony service involves many modules. All modules need to be enabled for full Telephony functionality.

DBUS Configuration

CONFIG_DBUS_DAEMON=y
CONFIG_DBUS_MONITOR=y
CONFIG_DBUS_SEND=y
CONFIG_LIB_DBUS=y

GLIB Configuration

CONFIG_LIB_GLIB=y

OFONO Configuration

CONFIG_LIB_ELL=y
CONFIG_OFONO=y
CONFIG_OFONO_RILMODEM=y  # modem type selection, choose rilmodem for rild support
CONFIG_OFONO_ATMODEM=y   # choose atmodem for serial/USB support

GDBUS Configuration

CONFIG_LIB_DBUS=y

Telephony API Configuration

CONFIG_TELEPHONY=y
CONFIG_TELEPHONY_TOOL=y  # debug tool, optional

TAPI Working Model

TAPI Usage Examples

Obtaining the TAPI Working Context

First declare a callback function:

static void on_tapi_client_ready(const char* client_name, void* user_data)
{
    if (client_name != NULL)
        syslog(LOG_DEBUG, "tapi is ready for %s\n", client_name);
    ...
}

Then call tapi_open to obtain the context. Successful acquisition requires oFono, D-Bus, and other services to be started successfully. The callback function is invoked when ready.

tapi_context context;
char* dbus_name = "vela.telephony.tool";
context = tapi_open(dbus_name, on_tapi_client_ready, NULL);

Releasing the TAPI Working Context

tapi_close(context);

Querying the Current Radio Power State

int slot_id = 0;
bool value = false;
tapi_get_radio_power(context, slot_id, &value);