diff --git a/README.md b/README.md
index 59adf07..337813d 100644
--- a/README.md
+++ b/README.md
@@ -309,6 +309,13 @@ number such as `+15555550123` is rejected with `21211`. Both scripts refuse to
 run with that placeholder once Twilio is configured, rather than spending a
 round trip to learn it.
 
+The destination is normalized before anything is sent, and both scripts echo
+the result — check that line first when Twilio rejects a number. Ten digits with
+no `+` are assumed US, so `8015601471`, `801-560-1471` and `+18015601471` all
+reach the same place. A `+` prefix is taken at its word: `+8015601471` is
+syntactically valid E.164 with country code `80`, so it passes normalization and
+is rejected by Twilio rather than here.
+
 A **real** `To` under test credentials is less predictable: some accounts accept
 it and return a synthetic SID, others answer `20404`
 (`resource ... Messages.json was not found`) despite the credentials being
diff --git a/scripts/sms-smoke.ts b/scripts/sms-smoke.ts
index 70caac8..441d8d3 100644
--- a/scripts/sms-smoke.ts
+++ b/scripts/sms-smoke.ts
@@ -93,6 +93,7 @@ async function main(): Promise<void> {
       ? `Twilio credentials present: real API call, From=${smsConfig().twilioFromNumber ?? smsConfig().twilioMessagingServiceSid}`
       : "No Twilio credentials: console adapter, nothing leaves the machine"
   );
+  console.log("To:", TO_NUMBER);
   console.log("Data dir:", process.env.NOTIFY_DATA_DIR, "\n");
 
   const app = express();
@@ -153,8 +154,10 @@ async function main(): Promise<void> {
     console.error(
       "\nNo devCode in the response, so the code never went out. The " +
         "code-send-failed detail above is Twilio's own words.\n" +
-        "  \u2022 'To' rejected: use a real number Twilio can validate, not a " +
-        "fictional 555-01xx one.\n" +
+        `  \u2022 'To' rejected (${TO_NUMBER}): check the country code — a US ` +
+        "number is +1 and ten digits (+18015601471, not +8015601471). Passing " +
+        "the ten digits with no + at all assumes US. Fictional 555-01xx numbers " +
+        "are rejected too.\n" +
         "  \u2022 'From' rejected (21606): under test credentials it must be " +
         "+15005550006; under live credentials it must be a number you own, or " +
         "a Messaging Service SID.\n" +