How do marketing agencies prove real ROI when leads come from phone calls?

Most marketing agency reports show clicks, forms, traffic, and conversions. But when someone actually calls, things get blurry.

We still hear things like:

“Yeah, we got some calls.”

“Not sure where they came from.”

“They probably came from Google.”

But calls are real leads. Real buyers. Real revenue.

So I’m curious how others handle this:

• Do you track where calls come from?
• Do clients ask about call data?
• Do you include calls in ROI reports or ignore them?
• How do you prove performance when calls are a big part of conversions?

Just trying to understand how agencies are handling this in real life — not theory, not tools, just real workflows.