Crushed SIM card -# is now active

6 months ago My boyfriend had a prepaid go phone with the same SIM and phone number for many years. He told me he “destroyed” his phone and SIM as too many spammers were calling. Then he got a new phone and number. 

For the heck of it- it texted his old number and someone replied. Is it possible his old number was “reassigned “ to a new customer?