SMS codes blocked during sign-up? It's a frustrating reality for many cross-border sellers. You sit down at your computer, ready to register for a new platform account, and the verification code never arrives. Or it finally shows up, only to greet you with a "too many requests" error. From my experience watching this industry, the problem rarely comes down to your internet speed or IP address. The real culprit is the phone number itself — it was likely flagged long before you ever had a chance to use it.
Here's a typical scenario. You just paid for an SMS receiving service, waited a few minutes, and the code finally landed. You hit submit — and the page instantly shows "restricted." It's tempting to blame your Wi-Fi or your VPN. But more often than not, that number was already tagged as high-risk by the platform from day one. No matter who tries to register with it, the result is the same.
Anyone in the industry knows a "number pool" is just a batch of real phone numbers held by an SMS receiving platform. So how do these numbers end up polluted? It comes down to three things.
Last year, I helped a friend who runs an independent ecommerce site figure out why his new accounts kept getting banned. When we pulled the backend data, we found that the SMS platform he was using had sold the same number to three different people within two days. And that same number had previously been used to sign up for more than a dozen overseas shopping sites. Every Facebook account registered through it got banned within seconds. That's textbook number pool pollution — and no amount of money spent on new numbers was going to fix it.
Once you understand the cause, the fix is straightforward. Cross-border sellers I work with agree that reliable providers exist, but you need a system to separate them from the rest. My advice is to look for three things: transparency, testability, and traceability.
Also, don't let a rock-bottom price win you over. Some providers look cheap on the surface but are really selling IoT cards or virtual operator number ranges. Those numbers are dead on arrival in the risk control systems of mainstream platforms. If a provider won't explain where their numbers come from, you're the one who ends up paying for it.
Some people ask: why not just buy physical SIM cards instead? You absolutely can, but there's no way to know if a card was previously banned, and managing dozens of physical cards comes with real overhead. What you actually need is a number service that's traceable, testable, and replaceable — not a one-shot gamble. That's why platforms like Getfollow have started making number sourcing and usage history transparent, so you have a clear picture before you commit.
Here's a quick reference to help you spot the difference between a clean and a polluted number pool.
| Signal | Clean Number Pool | Polluted Number Pool |
|---|---|---|
| Verification code delivery | Arrives within seconds or a couple of minutes | Late, delayed, or never arrives |
| Post-registration behavior | Accounts stay active without restrictions | Immediate verification prompts, limits, or bans |
| Number history | Provider shows past usage and source | Hidden, recycled, or shared with other users |
| Seven-day retention rate | Between 50% and 70% or higher | Below 50% and dropping |
Before you sign a long-term contract, run a small-scale test. Buy ten numbers, spread them across three to five platforms you actually use, and observe for a week. If your verification code delivery rate holds above 90% and none of your accounts get restricted, consider scaling up. Jumping straight into a monthly plan with hundreds of numbers is asking for trouble.
Long story short: blocked SMS verification codes almost always trace back to a polluted number pool. Instead of guessing and burning through test after test, start with a provider that is upfront about where its numbers come from. Remember the golden rule — test small first, then commit long-term. That's how you keep risk control issues in check without overpaying. When your accounts stay stable, your business does too.
It usually means the phone number you're using has already been flagged by the platform's risk control system. This happens when numbers have been resold multiple times, used for mass registrations, or linked to black-hat activity in the past.
A number pool is a batch of phone numbers owned or rented by an SMS receiving service. A pool becomes polluted when its numbers are overused, resold without tracking, or associated with fraud. Platforms mark those numbers as high-risk, which leads to blocked verification codes.
Buy a small batch of numbers, register on a few platforms you actually need, and track delivery rates plus account activity for about a week. A clean pool will deliver codes reliably and keep accounts active without restrictions. Seven-day retention rates between 50% and 70% are a solid benchmark.
Usually not. Low prices often signal recycled numbers or IoT-based number ranges that are already flagged by mainstream platforms. Paying a bit more for a transparent provider with verifiable number history is almost always the smarter move.
That error means the number itself hit a frequency limit or was flagged before you ever used it. Stop using that number right away and switch to a fresh one from a provider that lets you trace its history.