# telephony_data.h


## Overview

Defines C APIs for cellular data module.

**Library**: libtelephony_data.so

**System capability**: SystemCapability.Telephony.CellularData

**Since**: 13

**Related module**: [Telephony Data](ndk-apis-telephony-data.md)


## Summary


### Functions

| Name| Description|
| -------- | -------- |
| [OH_Telephony_GetDefaultCellularDataSlotId](ndk-apis-telephony-data.md#oh_telephony_getdefaultcellulardataslotid) | Obtains the default SIM card used for mobile data.|