In a little-known industry practice, wireless service providers routinely recycle former customers' phone numbers and give them to new customers without informing them of the number's history. ... A number can be reused within as little as 30 days.3 feb 2006
What happens to an old phone number?
The mobile carriers often recycle your old number and assign it to a new user. The telecom companies do it to stop number exhaustion, but this process is not safe for the users, who previously owned the numbers.4 may 2021