Create custom field on Phone Calls form which would be related to Marketing Campaign and then create a Saved Search to see the statistics.
User creates a custom CRM field which shows list of the Campaigns and sets the Campaign name on the Phone Call record. Then it is possible to use a Saved Search and get the summary of Phone Calls created against the Campaign.
Steps to create new custom field:
1. Navigate to Customization > Lists, Records & Fields > CRM Fields > New.
2. Enter Label e.g. Sale Calls from Campaigns.
3. Under Type select List/Record.
4. For List/Record field select Campaign.
5. Applies To subtab: check Phone Call checkbox to True.
6. For Display subtab select Subtab: Main, or according to the requirements.
Then review the Phone Call record: navigate to Activities > Scheduling > Phone Calls > New and there is a new dropdown field on the record. This way user can track the Sales Calls for Campaign.
To see the results, create a Saved Search with following steps:
1. Navigate to Lists > Search > Saved Searches > New.
2. Select Phone Call.
3. Enter Search Title e.g. Sale Calls from Campaign.
4. Check the Public, Available as List View, and Available as Dashboard View checkboxes to True (not necessary, it depends on user's requirements).
5. Under Criteria: Standard subtab the criteria might be determined according needed requirements.
6. Under Results subtab select fields user would like to be displayed. Make sure the created CRM Custom field is added.
7. Click Save and Run.