An SMS delivery receipt can't tell you who read it

What a delivery receipt records

An SMS delivery receipt is a network status update, not a report from the person you texted. It confirms that the message reached the recipient’s local cellular switching center—the part of the mobile network that handles connections and routes messages in that area.

That distinction matters because SMS is designed to pass through network equipment. A message can be accepted and routed within the cellular system without the receipt establishing what happened at the recipient’s phone. The receipt marks a delivery milestone in the network, not a completed conversation.

Why it cannot confirm a read

A phone being on, displaying the message, and a person reading it are separate events. A standard SMS receipt does not report the recipient’s screen or attention, so it cannot tell you whether anyone saw the text. It also does not prove that the recipient chose to ignore or answer it.

The receipt confirms network progress, not human awareness. In practical terms, it can reassure you that the message reached a point in the recipient’s cellular network—but it cannot tell you whether the message ever became something they read.