Firstly, create a "Custom Definitions" for the parameter the conversion is based on. Go to "Configure" => "Custom Definitions" and click "Create custom dimensions".
1.1. Enter a name such as "Unique_call" (without space).
1.2. The default scope is "Event". Do not change this value.
1.3. In the description, enter "Unique_call".
1.4. Select an event parameter such as "uniqueCall".
Let's set up the "Audience". Go to the "Configure" => "Audiences" section. And click "New audience".
2.1. Then click "Create a custom audience".
2.2. Enter a name for the new audience (for example, "Unique calls"). After that, set up the conditions:
2.2.1. Click "Events" and select call.
2.2.2. Add the "Unique_call" parameter that you created earlier.
2.2.3. For the conditions, select "exactly matches (=)" and set the value: "1".
2.2.4. Then specify the "Audience Trigger" without spaces. For example, "Unique_call".
Save the audience.
The last step is to set up conversion for this audience. Go to "Configure" => "Conversions". And click "New conversion event".
Give the conversion name the same as the audience trigger — "Unique_call" and save.
Conversion events are automatically enabled.

Written by Eugene Zastup
Updated over a week ago