Each phone carrier maintains a list of numbers that they determine to be spam risks based on the history of the number.
- Phone Numbers on this list will have a "spam" label attached to the Caller ID and displayed for any of the carrier's customers.
- These carriers update their lists periodically with phone numbers that have been reported to them. They also have their own internal requirements and will proactively label phone numbers based on factors such as: size, volume, rejection from their customers, etc.
Spam Registration Video