1# Telephony Data
2
3
4## Overview
5
6Provides C APIs for the cellular data module.
7
8**Since**: 13
9
10
11## Summary
12
13
14### File
15
16| Name| Description|
17| -------- | -------- |
18| [telephony_data.h](telephony__data_8h.md) | Defines C APIs for cellular data module.<br>**File to include**: \<telephony\/cellular_data\/telephony_data.h\>|
19
20### Functions
21
22| Name| Description|
23| -------- | -------- |
24| int32_t [OH_Telephony_GetDefaultCellularDataSlotId](#oh_telephony_getdefaultcellulardataslotid)(void) | Obtains the default SIM card used for mobile data.|
25
26## Function Description
27
28
29### OH_Telephony_GetDefaultCellularDataSlotId()
30
31```
32int32_t OH_Telephony_GetDefaultCellularDataSlotId(void)
33```
34
35**Description**
36
37Obtains the default SIM card used for mobile data.
38
39**System capability**: SystemCapability.Telephony.CellularData
40
41**Since**: 13
42
43**Returns**
44
45**0**: card slot 1.
46
47**1**: card slot 2
48