I am not receiving my phone number validation code

In case you are trying to validate your phone number in the SIGNL4 app but don't receive the validation/confirmation code message (SMS text), make sure that

1. You selected the right country code from the list
2.  Your phone number is entered correctly
3. Your country does not have regulation requiring an opt-in for (marketing) text messages.

India is an example for 3). Here you need to add your phone number to an opt-in database: http://www.nccptrai.gov.in/nccpregistry/