Sender ID

The name or number an SMS appears to come from, such as "Google" or a short code, instead of an ordinary phone number.

The sender ID is what shows in the "from" field of a text. Verification messages typically arrive from an alphanumeric name (WhatsApp, Google), a short code, or a long-code number, depending on the country's rules; several countries require pre-registered sender IDs for application traffic.

When you rent a number to receive a code, the sender ID is what helps you recognize which service the arriving SMS belongs to.