Articles on: Data Tools, Tracking Sources & Attribution

Tracking numbers and UTM parameters: how to track calls with custom UTMs

Manually assign UTM values to a tracking number so that every call to that number is attributed to the correct source in your reports.

This approach is best suited for static or source-level tracking.

E.g. Offline campaigns, print placements, or any situation where calls are not linked to website visits.

If you use Dynamic Number Insertion (DNI) for session-based tracking, UTM values are captured automatically from each visit and do not need to be assigned manually. Session-based UTM values will also take precedence over any manually assigned source if both are present.

Step 1. Create a custom parameter source.

Go to Data Tools > Sources.
Click + Add custom source.
Select Custom Parameters from the tracking source type menu.
Click Next.
Enter a name for this source.
Fill in whichever UTM fields apply: utm_source, utm_medium, utm_campaign, utm_term, utm_content, and/or referrer domain.
You do not need to fill in every field; only the parameters you define here will be populated for calls using this source.
Make sure the values match exactly what you want to see in reports (e.g. consistent use of lowercase).
Click Save.

Step 2. Assign the custom source to a tracking number.

Go to Tracking > Numbers.
Find the number you want to assign the source to.
Click the Source dropdown for that number.
Select your new custom parameter source.

Once assigned, all calls to this tracking number will report the selected UTM values until the source is changed or removed.

Editing a custom parameter source

Go to Data Tools > Sources.
Find your custom parameter.
Click to edit it.
Make your changes.
Click Save.

Changes to UTM parameters apply only to future calls. Historical call data will not be updated.

🎉 Your tracking number is now set up to report calls with your chosen UTM values.

Detailed guide: What are UTM parameters?

Detailed guide: DNI script 101: how to install and configure it

Updated on: 02/04/2026

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