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Bug Report: SMS Confirmation Fails for International Numbers ​

Bug ID: BUG-234
Reported By: QA Team
Date Reported: February 3, 2026
Environment: Production
Affected Version: v1.2.0

Summary ​

SMS confirmations are not being sent to users with international (non-US/Canada) phone numbers, leaving them without booking proof.

Severity Classification ​

Severity: 🔴 P1 (High)

Justification:

  • Affects 15% of users (international customers)
  • Core feature broken (SMS confirmation)
  • Workaround exists (email fallback triggers after 2 min)
  • Does not block bookings, but creates poor UX

Not P0 because: Booking still completes, email fallback works (albeit slowly)

Impact ​

Users Affected: ~750 bookings/month (15% of 5,000 total)

Business Impact:

  • Users call support asking "Did my booking go through?" (+50 tickets/week)
  • Poor NPS from international travelers
  • Blocks expansion to EU market

Steps to Reproduce ​

  1. Navigate to https://app.reserveeasy.com
  2. Complete booking flow for any restaurant
  3. At booking form, enter international phone number:
    • Example 1 (UK): +44 7911 123456
    • Example 2 (India): +91 98765 43210
    • Example 3 (Australia): +61 412 345 678
  4. Submit booking
  5. Check phone for SMS

Expected Behavior ​

What should happen:

  • SMS delivered within 30 seconds to the provided international number
  • SMS contains: restaurant name, date, time, party size, confirmation code, link

Actual Behavior ​

What actually happens:

  • SMS never arrives (even after 10 minutes)
  • No error message shown to user
  • User sees confirmation page (misleading - they think SMS coming)
  • Email fallback triggers after 2 minutes (too long - user already anxious)

Screenshot/Video ​

SMS Status Dashboard

Twilio Dashboard Error:

Error Code: 21211
Message: "The 'To' phone number +44XXXXXXXXXX is not a valid, SMS-capable inbound phone number."

Technical Details ​

Browser Console Errors ​

None - frontend doesn't detect the issue.

Network Request (API Call) ​

Endpoint: POST /api/v1/notifications/sms

Request Payload:

json
{
  "to": "+447911123456",
  "message": "Your booking at Bella Italia on 02/15/2026 at 7:00 PM for 4 guests is confirmed. Code: ABC123. Modify: https://app.reserveeasy.com/bookings/XYZ"
}

Response (500 Internal Server Error):

json
{
  "error": "SMS delivery failed",
  "details": "Twilio error 21211: Invalid destination number"
}

Server Logs ​

[2026-02-03 19:34:12] ERROR [SMSService] Twilio API error
Error Code: 21211
Message: The 'To' phone number +447911123456 is not a valid, SMS-capable inbound phone number.
Account SID: AC1234567890abcdef
Request ID: RM1234567890abcdef

Root Cause Analysis ​

Identified Issue: Twilio account is configured with US/Canada Geographic Permissions only. International SMS is disabled by default.

Why It Wasn't Caught Earlier:

  • Dev/Staging environments use US test numbers only
  • UAT testers were all US-based
  • International users started booking after EU marketing campaign launch

Reproduction Rate ​

Frequency: 100% reproducible with international numbers

Affected Phone Number Formats:

  • ✅ Works: US (+1), Canada (+1)
  • ❌ Fails: UK (+44), India (+91), Australia (+61), All EU countries (+3X series), etc.

Suggested Fix ​

Steps:

  1. Log into Twilio Console
  2. Navigate to Settings > Geo Permissions
  3. Enable SMS for:
    • Europe (all countries)
    • Asia Pacific (India, Australia, Singapore, etc.)
    • Latin America (if targeting)
  4. Test with +44, +91 numbers

Cost Impact: International SMS costs $0.05-0.15/message vs $0.0075 for US → ~10x cost
Mitigation: Only send SMS for high-value bookings (deposit required), use email for others

Option 2: Detect International Numbers & Use Email Only ​

Implementation:

javascript
if (phoneNumber.startsWith("+1")) {
  sendSMS(phoneNumber);
} else {
  sendEmail(email); // International users get email instead
}

Pros: No additional Twilio cost
Cons: Poor UX for international users (email slower, less likely to check)

Recommendation ​

Proceed with Option 1 - Enable international SMS for better UX. Cost increase is ~$40/month (800 intl bookings × $0.05) which is acceptable given $120k monthly revenue.

Priority & Timeline ​

Assigned To: Backend Team (Sarah, Lead Engineer)
Target Fix Date: February 8, 2026 (before EU marketing push)
Dependencies: None - Twilio config change only

Verification Plan ​

After fix deployed:

  1. Manual Test:

    • Complete booking with +44 7911 123456 (UK number using Twilio test mode)
    • Verify SMS delivered within 30 seconds

  2. Automated Test:

    • Add integration test for international SMS delivery
    • Run nightly

  3. Monitor:

    • Track SMS delivery rate by country code for 7 days
    • Alert if delivery rate <95%
  • BUG-189 - Email fallback takes 2 minutes (should be 30 seconds)
  • FEATURE-067 - Allow users to choose SMS vs Email preference

Sign-Off ​

Bug Verified By QA: ___ Date: ___
Fix Deployed to Production: ___ Date: ___
Bug Closed: ___ Date: ___

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