I want to create generic response codes, for an API that I am developing. Now I know there are HTTP response codes that are usually recommended to be used, but my API will be handling multiple USSD gateway responses.
So a generalized mapping of response codes within API will highly be useful. After brief Googling I didn't come up with a document or article on best practices while deciding response codes (Whether it should be numeric, alphanumeric, length etc).
Any help or suggestion will highly be appreciated.