If you are trying to bypass OpenAI's SMS verification wall for Codex or ChatGPT, stop buying the cheapest phone numbers available. A new analysis of fulfillment data from August and September 2026 demonstrates that low-cost numbers, often sold for as little as $0.01 on wholesale aggregators, suffer from abysmal delivery rates due to aggressive fraud flagging by OpenAI's risk models.

The Cost of Bargain Bin Verification

The dataset, compiled by a small operator named Codex SMS, tracked 31 paid buyers and over 100 activations across 26 countries. The findings are stark: while US and Japan numbers showed the highest success rates in a dedicated pool, the broader market tells a different story. During the initial multi-country testing phase, only 57.7% of buyers (15 out of 26) successfully completed verification. The numbers sold in the bargain tier—those costing between one and five cents—correlated directly with the highest failure rates, proving that price is inversely related to reliability in this ecosystem.

Why OpenAI Blocks Cheap Segments

Public SMS marketplaces typically sort by price, pushing heavily recycled carrier prefixes to the top of the list. These segments have been queried hundreds of times, triggering OpenAI's fraud detection heuristics. The data shows a clear clustering of success among countries with cleaner reputation scores, such as the United States and Japan, where fresh telecommunications prefixes remain unflagged. Conversely, Portugal performed the worst in the dataset with a mere 5.4% success rate across 37 activations, while twenty other countries hovered in the near-zero range of 0% to 7%.

Latency and Operational Realities

Success isn't just about delivery; it's about timing. The data highlights significant latency differences that trip up users. US numbers averaged a wait time of 164 seconds, while Japan numbers averaged 487 seconds—nearly eight minutes. Many users cancel their attempts after 60 seconds, discarding numbers that would have eventually delivered the code. The operator advises switching regions immediately after two consecutive failures to avoid triggering temporary rate limits on the registration IP, which can compound the problem.

Key Takeaways

  • Prioritize clean prefixes over price: US and Japan routes cost more ($0.30–$0.66) but deliver reliably.
  • Account for latency: Japan's 487-second average wait time requires patience, not cancellation.
  • Stop spamming: Two consecutive failures should trigger an immediate region switch to avoid IP throttling.
  • Bind TOTP immediately: Use the temporary number only for initial verification, then secure the account with an authenticator app.

The Bottom Line

OpenAI's fraud models are winning the war on cheap verification. If you want a Codex account that sticks, pay the premium for clean US or Japan prefixes instead of gambling on recycled, five-cent numbers.