alt Hacker NewsYou can verify a phone number is real and active without needing them to reply, or without someone even receiving a notification.
1) SMS supports receipt functionality, which means the sender can be notified when a message is delivered to a handset. This happens at the carrier level, so you can't turn it off.
2) SMS supports 'silent' messages which are a different message class that is not shown to users.
Replies
toast0 • 10/01/2024
Receipts are unreliable. Carriers and aggregators regularly filter or fake them.
Receiving a receipt is not a real indication of delivery, and absence of receipt is not a real indication of absence of delivery.
True, however, "delivered to a device" and "there's someone reading and replying at the other end" are two different confidence levels of "active".
You could, for instance, be texting an unattended device.