Hi! “Can’t receive SMS verification code” usually comes down to one of three buckets: the service isn’t actually sending, the carrier is filtering the code (often short-code SMS), or the phone is hiding/blocking it.

To keep this safe (no account lockouts, no “remove your number” steps), tell me:
1) Which service is failing most (Microsoft/Google/Apple/bank/social)?
2) Are you on iPhone or Android?
3) Do you receive normal texts from people, and do you receive any one-time passwords (OTP) from other apps?

You’re thinking about it the right way. Repeated “resend code” clicks can trigger cooldowns on some accounts, so we’ll diagnose first.

Quick clarifiers that help narrow it fast:
• Is your phone number a normal mobile SIM number (not a VoIP/virtual number)?
• When you request the code, does it come from a 5–6 digit short code, or a full phone number (if you’ve ever received one)?
• Did this start after anything changed: new carrier, number port, SIM/eSIM change, iOS update, or traveling/roaming?

That pattern is very telling: person-to-person SMS works, some OTP texts work, but specific services’ codes don’t. After a number port, short-code routing and carrier spam filtering can behave differently than regular texts for a while.

Let’s do “safe checks” that don’t mess with your account security settings:

1) Look for hidden messages: On iPhone Messages, do you use “Filter Unknown Senders”? If yes, check the “Unknown Senders” list when you request a code (OTP texts often come from unknown senders).

2) Blocked senders: In iPhone settings, check if any numbers are blocked. Even one blocked short code can make it feel like “codes never arrive.”

3) Compare conditions: Request the code once when you have strong cellular signal (not basement/parking/weak LTE). Weak signal can delay short-code SMS even when iMessage and Wi-Fi stuff seems fine.

Perfect — we can use that to separate “delivery” from “filtering.” If it’s not in Unknown Senders, then either the message isn’t reaching the phone at all, or it’s being filtered earlier (carrier-level or app-level).

A low-risk diagnostic sequence (no password changes, no removing your phone number):

• Timing check: When your bank OTP arrives, does it arrive instantly or with a delay (like 1–3 minutes)? Delays suggest routing/signal, not necessarily a block.

• Network condition check: Do one test request with strong cellular signal and without relying on Wi-Fi calling (just for a test). If outcomes change, it hints at routing/coverage differences.

• Sender-type check: If two different services never arrive (Microsoft + gaming app), that often points to a shared short-code route or filtering rule rather than a single app glitch.

When you request the Microsoft code, does it show any “try again later” message or timer, or does it let you request over and over?

The timer/cooldown is normal after multiple attempts — it’s a security behavior, not you doing something “wrong.” Also, seeing correct last digits is good, but there are still two subtle gotchas we can check safely:

1) Country/format mismatch: Some accounts store the number with a country code. If the account is set to the wrong country/region, OTP delivery can fail even if the last digits look right.

2) Old number on file elsewhere: Some services can have multiple verification methods saved (old phone, backup phone). If you’re seeing only SMS, it may still be sending to the right one — but it’s worth confirming there isn’t a second number hidden in security info.

Not asking you to change anything — just confirm what you see. Are you signing in on the same iPhone that has the SIM, or on a laptop/browser and waiting for the SMS on the iPhone?

Thanks — that setup is common, and it helps us keep the testing controlled. Since you’re waiting on the phone, we can focus on delivery to the iPhone line.

Here’s what I’d avoid so you don’t get stuck in a lockout loop:
• Don’t keep hitting “send code” repeatedly (cooldowns can get longer).
• Don’t remove your phone number from the account while you can’t receive codes.
• Don’t “wipe/reset network settings” as a first move — that’s disruptive and usually not necessary for diagnosis.

Safe checks that won’t change your account:
• Verify the iPhone can receive other short-code messages today (you already saw the bank one, even if delayed).
• Check whether any SMS spam filtering or “block unknown” feature is enabled in a carrier app/plan feature (it can affect automated codes more than normal texts).
• Note whether delays happen only in low-signal areas — short-code OTP is less forgiving than regular messaging.

Yes — you can gather evidence without changing anything.

Carrier-filtering clue checklist (safe):
1) Some short codes arrive (bank) but certain brands never arrive (Microsoft + gaming). That split often suggests route-specific filtering, not a broken phone.
2) Messages arrive delayed more often in low signal areas. That points to delivery reliability, not just “blocked.”
3) Unknown Senders is empty during the test — meaning it’s not simply being hidden by iPhone filtering.

If you can, do one controlled test later: request one code, wait a reasonable time, and note whether you see a cooldown timer. Don’t brute force it. The result helps distinguish “service rate limit” vs “SMS delivery issue.”

One more question: do you have any second device (old phone) still logged into the account that could receive a push prompt instead of SMS, or is SMS the only option everywhere?

Most likely causes (based on your symptoms) — still diagnosis, not “do this and it’s fixed”:

• Short-code delivery/routing after a number port (especially when some OTP texts are delayed and others never arrive).
• Carrier spam protection or message blocking affecting automated verification SMS more than normal texts.
• Weak cellular signal at the moment of delivery (basements and 1-bar LTE can silently drop time-sensitive OTP messages).
• Service-side cooldown/security hold after many resend attempts (explains timers).
• Number/region detail mismatch (country code/region stored in the account).

If you keep notes on (1) whether bank OTP is delayed vs instant, (2) whether Microsoft never arrives across multiple days, and (3) whether Unknown Senders stays empty, you’ll have a clear picture of the bucket you’re in — without making risky account changes.