HTTP 400 · Bad Request
HTTP 400 Authentication

When & why it happens

The phone number is not yet being used. Treated by gogram as a regular API error; inspect ErrResponseCode.Message for the exact code.

Handling in gogram

Surfaced as *gogram.ErrResponseCode. Match on the message:

if err, ok := err.(*gogram.ErrResponseCode); ok { if err.Message == "PHONE_NUMBER_UNOCCUPIED" { // handle this error } }