ContactMessaging
Details
Android App developed in Kotlin
One extended function used (For generating random 6 digit number)
No 3rd party library used
Status
Right now code doesn’t support instant permissions for Android SDK greater than 23. (Might get updated till you read it so you can check the code on github)
Twilio is not free and I ended up blocking myself on Nexmo , so I used android.telephony.SmsManager