Most "my UK eSIM is broken" tickets land in support with the SIM working fine — the issue is almost always one of ten settings on the phone or one of two things on the sender side. Here is the troubleshooting checklist we use ourselves before escalating any case. Run through it in order; in our data, 95% of issues resolve at step 5 or earlier.
The 30-second triage
- Is the eSIM showing as "Active" / "Connected" in your phone Settings?
- Do you have data or Wi-Fi connectivity right now?
- Is the BuyUKeSim line set as the default for SMS (on dual-SIM phones)?
- Did the sender use country code +44?
- Is your line still in date — top-up not lapsed?
If all five are "yes", proceed to the full checklist below.
1. Confirm the eSIM is provisioned and active
iPhone: Settings → Cellular → tap the BuyUKeSim line → status should read "Active" with a UK MNO name (EE, O2, Vodafone, Three, or our partner MVNO).
Android: Settings → Network & Internet → SIMs → tap the BuyUKeSim line → confirm "Use SIM" toggle is on and signal indicator is present.
If status reads "Not Activated" or "No Service", the eSIM has not registered to the UK network. Reboot the phone with airplane mode off, then check again. If still failing, message support — the QR may need to be reissued.
2. Set the BuyUKeSim line as default for SMS
This is the single most common cause of "no SMS arriving". On a dual-SIM phone, your other SIM is still set as the default for messages — the WhatsApp/Binance/Tinder code is sent to your UK +44 number, but the phone routes incoming SMS through your primary line, never showing the +44 SMS in the Messages app.
iPhone: Settings → Cellular → Default Voice Line / Cellular Data — leave Voice and Data on your normal line, but tap "Cellular Plans" and ensure the BuyUKeSim plan has "Allow Cellular Data Switching" enabled. Then under iMessage and FaceTime settings, make sure the +44 number is one of the addresses.
For SMS specifically: open Messages → New Message → tap your contact's name → "Send From" — choose the BuyUKeSim line. iOS does not have a global SMS default, but it remembers per-conversation.
Android: Settings → SIMs → "SMS messages" — pick the BuyUKeSim line.
3. Wait the realistic delivery window
SMS is not instant. Typical UK MNO inbound SMS arrives in 5–30 seconds. Outliers (Binance during heavy load, or a poorly configured corporate sender) can take 1–4 minutes. If you panic-resend three times in 10 seconds, three codes will arrive together — the first two are already invalid by the time you read them.
4. Check that the sender used +44
Some apps (notably PayPal in some flows, and a few smaller fintechs) auto-pick the country code based on your IP geolocation rather than the number you entered. If you signed up while on a Berlin IP, they may have sent the SMS to +49 [your UK digits] — which goes nowhere.
Fix: in the app, manually choose United Kingdom or +44 in the country dropdown before entering the number.
5. Confirm your line is in credit
BuyUKeSim lines stay active by top-up. If your line has lapsed, incoming SMS will be silently dropped at the network — no error, no bounce, the SMS just disappears. Log into your account / order status page and check expiry. If it has expired, top up first, then ask the sender to retry.
6. Disable SMS filtering on iOS
iPhone: Settings → Messages → Unknown & Spam → turn off "Filter Unknown Senders" while you are testing. iOS occasionally hides SMS from short codes (5- or 6-digit senders, used by all banks and exchanges) under "Unknown Senders" — you may have the SMS, but the Messages tab is filtering it.
7. Check Android's spam filter
Android: Open Messages → menu → Spam & blocked → review. Google Messages and Samsung Messages both have ML spam filters that occasionally catch verification codes. The SMS is in the spam tab, not the inbox.
8. Disable airplane mode and re-toggle cellular
If the eSIM was active but signal is now poor (you walked into a basement, switched countries on the same flight, etc.), the line may be deregistered. Toggle airplane mode on for 10 seconds, then off. Wait for the signal indicator to return before re-requesting the SMS.
9. Confirm the app is using your UK number, not your old one
Common in account-recovery flows: the app remembers your previous registered number. The verification SMS is being sent to that old line, not the new +44. Check your account settings for the registered number; update it to the BuyUKeSim line first if needed.
10. Some senders block any "premium" or "non-fixed" line
Rare, but real. A handful of US and Canadian senders refuse to deliver SMS to non-domestic mobile numbers as part of their fraud rules. If you have already verified the steps above and SMS still does not arrive from one specific service, contact that service's support — the issue is on their side, not yours.
What if voice OTP is offered?
Many apps (Binance, Coinbase, PayPal) offer a "Call me with the code" fallback if SMS fails. The BuyUKeSim line accepts incoming voice calls. If SMS is genuinely refusing, switch to voice OTP and your code will arrive as a robocall.
Still nothing — when to message support
If you have completed steps 1–10 and the SMS is still missing, contact us via Telegram or the contact form. Include:
- Your order ID
- The exact app/service the SMS is from
- The country/IP you are signing up from
- Phone model + OS version
- Whether you have a screenshot of the "code sent" confirmation in the app