1. Two-Phase USD Wallet Accounting (Available vs. Reserved)
Unlike traditional platforms that immediately deduct your balance the moment a phone number is displayed on screen, NEXUSOTP uses an atomic two-phase ledger denominated in micro-USD (1,000,000 micro = $1.00 USD):
| Ledger State | Trigger Event | Available Balance | Reserved Balance | Final Outcome |
|---|---|---|---|---|
| 1. Quote Confirmed | You click Confirm & Rent |
-$0.25 USD |
+$0.25 USD |
Funds held safely in escrow for up to 600s |
| 2A. SMS Received | OTP arrives within 10 mins | Unchanged | -$0.25 USD |
RENTAL_CHARGE_FINAL recorded |
| 2B. 10-Min Timeout | Zero SMS after 600 seconds | +$0.25 USD |
-$0.25 USD |
RENTAL_REFUND_EXPIRED (100% refunded) |
| 2C. Out of Stock | Carrier pool busy at allocation | Unchanged ($0.00 charged) |
Unchanged | Instant notification to try another country |
2. Why Manual Mid-Session Cancellation Is Disabled
International A2P SMS packets frequently take 15 to 90 seconds to traverse cross-border SS7/SMPP hops. Allowing manual cancellation at 15 seconds causes race conditions where an SMS arrives at second 18 after the number was released. By enforcing a uniform 10-minute (600-second) session window, our gateway guarantees that delayed international SMS codes are still captured while guaranteeing a 100% automatic refund if no message ever arrives.