Normalize fax numbers to a consistent format
Remove spaces, dashes, parentheses, and fax lists other formatting differences.
Convert all text fields (business names, contact names) to a common case (upper or lower) for easier comparison.
2. Use Spreadsheet Tools or CRM Features
Import all lists into one master spreadsheet or your CRM.
Use built-in “Remove Duplicates” features:
Excel/Google Sheets: Use the “Remove duplicates” tool on the fax number column.
CRMs often have deduplication tools based on phone/fax numbers or emails.
3. Compare Multiple Fields for Accuracy
Don’t just rely on fax numbers — cross-check business name, address, and contact person.
Sometimes the same fax number is listed differently (e.g., branch offices vs. headquarters).
Flag these for manual review.
4. Leverage Dedicated Data Cleaning Tools
Use tools like OpenRefine, Data Ladder, or Informatica for advanced matching and fuzzy duplicates detection.
These tools help catch near-matches and formatting inconsistencies that simple filters might miss.
5. Create a Unique Identifier
Combine multiple fields (e.g., fax number + business name) into a single identifier to catch duplicates that have slightly different details.
6. Set Rules for Which Record to Keep
Decide in advance which list takes priority if duplicates are found:
Most recent update?
More complete contact info?
Opt-in status?
7. Regularly Update and Clean Your Master List
Schedule ongoing deduplication every 3-6 months.
Remove invalid or bounced fax numbers as they come in.
8. Document Your Process
Keep notes on how and when you merged lists.
Track sources and dates to ensure transparency and compliance.
Final Thought:A clean, duplicate-free fax list not only saves money but also boosts campaign effectiveness and keeps you legally compliant.
Need help creating a deduplication workflow or a script to automate the process?