---
title: "Check that a number still belongs to the · Agent Wranglers"
url: https://agentwranglers.se/playbook/notifications/text-messages/reassigned-numbers
updated: 2026-10-21
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Check that a number still belongs to the person

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Text messages](https://agentwranglers.se/playbook/notifications/text-messages.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers). Updated 2026-10-21.

- Level: Recommended
- Chapter: [Text messages](https://agentwranglers.se/playbook/notifications/text-messages)
- Rule: Before you text a number whose consent is older than the last check, confirm the number has not passed to someone else. Suppress it when it has.
- How: Carriers give disconnected numbers to new owners, and a text to the old owner's number then reaches a stranger. In the US, query the FCC's Reassigned Numbers Database with the number and the date consent was given. Under 47 CFR 64.1200(m), a sender who queried it and got "no" is not liable when that answer was wrong. Store each query's date and answer next to the consent row. Elsewhere, suppress a number on a carrier's "unknown subscriber" error, as [Track what happened to each text](https://agentwranglers.se/playbook/notifications/text-messages/sms-delivery-status) says. Ask people to confirm their number with a code when it has been unused for a long time, such as 12 months. Keep the proof of consent as the [consent records rule](https://agentwranglers.se/playbook/email/email-privacy/consent-records) shows.
- Check: A test feeds the send job a US number that the database stub marks as reassigned. No text is sent, and the number is suppressed. A query finds no US text sent without a database check dated after the consent.

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### SQL example

```sql
-- Must return 0 rows: US texts sent with no reassigned-number check after the consent date
SELECT s.id FROM sends s
JOIN consents c ON c.user_id = s.user_id AND c.channel = 'sms'
LEFT JOIN number_checks n ON n.phone = s.phone AND n.checked_at > c.given_at AND n.checked_at <= s.sent_at
WHERE s.channel = 'sms' AND s.phone LIKE '+1%' AND n.phone IS NULL;
```

### JavaScript example

```js
export async function mayTextUsNumber(phone, consentGivenAt) {
  const answer = await reassignedNumbers.query({ number: phone, date: consentGivenAt }); // 'yes' means the number changed hands
  await db.numberChecks.insert({ phone, answer, checkedAt: new Date() });
  if (answer === 'yes') await db.smsSuppressions.add(phone);
  return answer === 'no';
}
```

### Python example

```python
from datetime import UTC, datetime

def may_text_us_number(phone: str, consent_given_at: datetime) -> bool:
    answer = reassigned_numbers.query(number=phone, date=consent_given_at)  # "yes" means the number changed hands
    db.number_checks.insert(phone=phone, answer=answer, checked_at=datetime.now(UTC))
    if answer == "yes":
        db.sms_suppressions.add(phone)
    return answer == "no"
```

## Sources

- [47 CFR 64.1200, Delivery restrictions](https://www.ecfr.gov/current/title-47/chapter-I/subchapter-B/part-64/subpart-L/section-64.1200)

## Related rules

- [Track what happened to each text](https://agentwranglers.se/playbook/notifications/text-messages/sms-delivery-status) in Notifications
- [Keep proof of consent](https://agentwranglers.se/playbook/email/email-privacy/consent-records) in Email

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/notifications/text-messages/reassigned-numbers">Agent Wranglers notifications playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Track what happened to each text](https://agentwranglers.se/playbook/notifications/text-messages/sms-delivery-status)
- [Text messages](https://agentwranglers.se/playbook/notifications/text-messages)