Can not detect US/UK phone number as PII

Question

Can not detect US/UK phone number as PII

Mohsin Khan 60

Hey,

Greetings,

Below numbers are not detected as PII for US/UK . please suggest how should proceed ?

UK: +66 1234 567890
US: (123) 456-7890

SriLakshmi C 6,250 Reputation points Microsoft External Staff Moderator

2025-05-21T16:06:47.7666667+00:00

Hi @Mohsin Khan,

Following up to see if the below answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

Thank you!
Danny Dang 90 Reputation points Independent Advisor

2025-05-22T07:23:37.2633333+00:00
Hi Mohsin,

Thank you for reaching out and for bringing this to our attention.

We understand your concern regarding the phone numbers not being detected as PII (Personally Identifiable Information) by Azure AI Language for the US and UK formats:

UK: +66 1234 567890

US: (123) 456-7890

Upon review, it appears that the number labeled as "UK" is actually using the +66-country code, which corresponds to Thailand, not the UK. Azure AI Language PII detection uses Named Entity Recognition (NER) to identify sensitive data like phone numbers, and it relies on both format and contextual cues to determine whether a number is considered PII 1.

If a number doesn't match the expected pattern for a specific region (e.g., UK or US), or lacks sufficient context, it may not be flagged as PII. This could explain why the examples provided were not detected.

Suggested Next Steps:

1. Verify the Format and Context: Ensure that the phone numbers are in a format that aligns with the regional standards (e.g., UK numbers typically start with +44).

2. Use Region-Specific Configuration: If you're using the Azure AI Language API, consider specifying the appropriate locale or region in your request to improve detection accuracy.

3. Custom Recognizers: If your use case involves detecting non-standard or international formats, you might benefit from implementing custom recognizers using tools like Microsoft Presidio, which allows for more flexible and tailored PII detection.

If I have answered your question, please accept this as answer as a token of appreciation and don't forget to thumb up for "Was it helpful"!

Warm regards,
SriLakshmi C 6,250 Reputation points Microsoft External Staff Moderator

2025-05-22T11:42:55.81+00:00

Hi @Mohsin Khan,

Just checking to see if you had a chance to review the below response.

Do let me know if that helps or have any other queries.

If the response helped, please do click Accept Answer and Yes for was this answer helpful.

Thank you!

1 answer

Your answer

SriLakshmi C 6,250 Reputation points Microsoft External Staff Moderator

2025-05-21T16:06:47.7666667+00:00

Hi @Mohsin Khan,

Following up to see if the below answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

Thank you!
Danny Dang 90 Reputation points Independent Advisor

2025-05-22T07:23:37.2633333+00:00

Hi Mohsin,

Thank you for reaching out and for bringing this to our attention.

We understand your concern regarding the phone numbers not being detected as PII (Personally Identifiable Information) by Azure AI Language for the US and UK formats:

UK: +66 1234 567890

US: (123) 456-7890

Upon review, it appears that the number labeled as "UK" is actually using the +66-country code, which corresponds to Thailand, not the UK. Azure AI Language PII detection uses Named Entity Recognition (NER) to identify sensitive data like phone numbers, and it relies on both format and contextual cues to determine whether a number is considered PII 1.

If a number doesn't match the expected pattern for a specific region (e.g., UK or US), or lacks sufficient context, it may not be flagged as PII. This could explain why the examples provided were not detected.

Suggested Next Steps:

1. Verify the Format and Context: Ensure that the phone numbers are in a format that aligns with the regional standards (e.g., UK numbers typically start with +44).

2. Use Region-Specific Configuration: If you're using the Azure AI Language API, consider specifying the appropriate locale or region in your request to improve detection accuracy.

3. Custom Recognizers: If your use case involves detecting non-standard or international formats, you might benefit from implementing custom recognizers using tools like Microsoft Presidio, which allows for more flexible and tailored PII detection.

If I have answered your question, please accept this as answer as a token of appreciation and don't forget to thumb up for "Was it helpful"!

Warm regards,
SriLakshmi C 6,250 Reputation points Microsoft External Staff Moderator

2025-05-22T11:42:55.81+00:00

Hi @Mohsin Khan,

Just checking to see if you had a chance to review the below response.

Do let me know if that helps or have any other queries.

If the response helped, please do click Accept Answer and Yes for was this answer helpful.

Thank you!

Answer 1

Hello @Mohsin Khan,

I understand that Azure AI Language’s PII detection may not be identifying certain entities such as Italian driver’s license numbers, VAT numbers, or even US/UK phone numbers due to limited locale coverage or formatting inconsistencies.

Currently, enhanced PII detection is available primarily for specific locales like the US, UK, Canada, and India. For countries like Italy, detection for identifiers such as AB1234567 or IT12345678901 is not natively supported in the prebuilt models.

Phone numbers may fail to be detected if they are not in recognized formats. For instance, a UK phone number using the country code +66 (which belongs to Thailand) may cause detection to fail, while US numbers should follow standard formats like (123) 456-7890 or +1 123-456-7890 for better accuracy.

To address these, you can:

Implement Custom Named Entity Recognition (NER) using Azure Language Studio to detect country-specific patterns.

Apply regex-based filtering as a pre- or post-processing step to catch unsupported PII types.

Ensure correct locale settings are used (e.g., "it-IT"), even though some locales have limited PII support.

Submit feedback via Post idea · Community to help prioritize broader international PII coverage.

Please refer this Category: Phone Number.

I Hope this helps. Do let me know if you have any further queries.

If this answers your query, please do click Accept Answer and Yes for was this answer helpful.

Thank you!

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Can not detect US/UK phone number as PII

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