For cases like this, I use https://usreversephonelookups.com/ . It can show whether the number still exists, who the owner might be, and sometimes even confirm the general region. When I was looking for an old friend, the service gave me a hint that the number was still active and belonged to a private individual. This helped me realise that it was worth trying to send a text message. Maybe you'll be lucky enough to find someone you haven't spoken to in a long time.