How to set Assamese language as default keyboard in Micromax Q300

Know from our experts how to set your default keyboard to Assamese in your Android smartphone.

I have been using the device Micromax Q300 since two years. I have tried changing the default keyboard language, but the Assamese language does not appear in the list of languages.

The device is Android Lollipop,
Processor - 1.2 GHz Quad-core
Screen. - 8.89cm(3.5)HVGA Screen
Memory - 4GB ROM 521MB RAM
Camera - Rear 2.0MP Front 0.3MP
OS - Android Lollipop
Connectivity- Wi-Fi 802.11 b/g/n | Bluetooth
Better - 1200 mAh
Bands - GSM 850/900/1800/1900 MHz (2G) WCDMA 900/2100 MHz (3G)
M_IME l1: 911507204216743
SIMEI2 : 911507204216750
EAN NO: 8904132431515
SN : VO331616063700103638
Colour: Champagne

So, how can I set Assamese as the default language in my smartphone?