"Not Delivered" to an Android Number: What It Actually Means

“Delivered” means three different things

Before diagnosing a failure, it helps to know that the status line under your message is reporting on three different systems depending on the conversation, and they have different levels of honesty.

On iMessage, “Delivered” means Apple’s service handed the message to their device and the device acknowledged it. This is a strong, reliable signal.

On RCS, “Delivered” means much the same thing: their device received it and said so. Also strong.

On SMS, “Delivered” means the network sent back a delivery report — if both carriers support delivery reports and chose to pass one along. Many do not. On SMS, the absence of “Delivered” frequently means nothing at all, because the confirmation was never going to arrive in the first place.

So the first useful question is which protocol you were on. A missing status on SMS is unremarkable. A “Not Delivered” on iMessage or RCS is a real signal. Our checker will tell you which one applies.

The six causes, most likely first

1. They have no connection right now

The most common by a wide margin and the most boring. Tunnel, lift, aeroplane, dead battery, no data left, a place with no coverage. The message will deliver when they come back.

How to tell: it eventually delivers on its own without anyone doing anything. If a message sat as Not Delivered for two hours and then went through, this was it.

2. Their number is still registered to iMessage

This is the one specific to Android, and it is the reason this guide exists. If someone moved from an iPhone to an Android phone without deregistering, their number is still on Apple’s iMessage register. Your iPhone sees that, decides to send an iMessage, and sends it into a service they no longer use.

How to tell: the bubbles are blue when they should be green, and the failures are consistent rather than occasional. Also strongly suggested if you know they recently changed phones.

Fix: it is on their side. Send them this. Meanwhile, on your end, delete the conversation entirely and start a new one — that clears the cached routing on your phone and often fixes it immediately.

3. Their RCS registration is stuck

If their RCS is half-registered, messages can be attempted over RCS, time out, and fail before falling back to SMS properly.

How to tell: intermittent. Some messages go, some do not, with no pattern you can see. Often started right after they changed SIM or carrier.

Fix: theirs. The six-step sequence is here.

4. Your own fallback is switched off

Your phone has a setting controlling whether it retries as a plain text when the modern route fails. If that is off, failed messages just sit there rather than getting through in a degraded form.

How to tell: failures across multiple different contacts rather than one person. That points at your phone rather than at any of them.

Fix: yours, and it is quick. Turn the fallback back on in your messaging settings.

5. The number is wrong, disconnected, or not a mobile

A digit off, a number that has been reassigned, or a landline. Landlines cannot receive texts, and your phone has no way to know it is a landline before it tries.

How to tell: it has never worked with this number, as opposed to having stopped working.

6. Carrier-level filtering

Networks filter messages they classify as spam, and the classifiers are imperfect. Messages containing links, unusual characters, or the same content sent to many people can be caught.

How to tell: rare for personal messages, more common if you sent something link-heavy or messaged many people at once. Try sending a short plain-text message to the same person — if that goes through, the content was the problem.

The blocking question, answered honestly

You are probably here because of this, so here is the straight version.

You generally cannot tell whether you have been blocked, and any method claiming otherwise is guessing.

Blocking on both platforms works on the receiving end. Their phone accepts your message and then declines to show it to them. Your phone is not informed — being informed would defeat the purpose. So a blocked message usually looks exactly like a delivered one.

What people wrongly treat as evidence:

• “Delivered” disappeared. It can also disappear because they turned off their phone, changed carrier, ran out of data, or moved to a phone that does not report delivery. On SMS the report may never have been reliable to begin with.
• The bubble turned green. Green means the message is not going over iMessage. That happens when someone switches to Android, turns iMessage off, or has no data. The long version.
• Calls go straight to voicemail. Also what happens when a phone is off, in Do Not Disturb, in focus mode, or in a dead zone.

What is weakly suggestive, taken together: every message failing consistently for weeks, calls always going straight to voicemail after one ring, and no response through any other channel — while that person is demonstrably active elsewhere. That is a pattern rather than proof, and it can still be a phone that died and was replaced with a new number.

What is definitive: asking them, or hearing from a mutual contact. There is no technical test that substitutes for this, and the internet’s confidence on this point is not matched by the technology.

If someone has blocked you, the correct response is to stop trying to determine it technically and respect the answer.

A quick sequence when nothing is working

1. Send to a different person. If that fails too, the problem is your phone or your line, not them.
2. Delete the conversation and start a new one. This clears cached routing and fixes the stale-iMessage case.
3. Toggle aeroplane mode on and off to force a fresh network registration.
4. Check your own fallback setting is on.
5. Ask them through any other channel what they see on their end. Two minutes of this beats two hours of inference — the failure is often obvious from their side and invisible from yours.

Version facts on this page: not verified yet — the site-wide verification pass has not been completed. See the update log

Related guides

• Not Getting Texts After Switching from iPhone to Android
• RCS Stuck on "Connecting" or "Setting up"? Here's Why
• Do Read Receipts Work Between iPhone and Android?
• The full feature-by-feature comparison

Published 1 September 2026. Last reviewed 1 September 2026. This guide depends on facts F22, F23, F13 in our verification table — if one of those changes, this page gets rewritten and the change is logged in the update log.