Short code

A 4-6 digit number used by businesses to send high-volume SMS like verification codes; can send but not receive like a normal number.

Short codes are abbreviated numbers (like 32665) leased for application messaging in a specific country. They handle high throughput and are hard to spoof, which is why large platforms send verification codes from them in markets like the US.

They are sender-side infrastructure: you receive from short codes on a rented number, but numbers you rent are ordinary long codes.