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# 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](https://app.nimbata.com/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**.

![](https://storage.crisp.chat/users/helpdesk/website/-/2/f/4/5/2f459a49cf382400/image_1t302eg.png)

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

* Go to [Tracking > Numbers](https://app.nimbata.com/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](https://app.nimbata.com/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?**](https://help.nimbata.com/en/article/what-are-utm-parameters-1vykgp0/) 
Detailed guide: [**DNI script 101: how to install and configure it**](https://help.nimbata.com/en/article/dni-script-101-how-to-install-and-configure-it-1l7zt51/)