Is a "Call Now" button next to a phone number nessessary for mobile users?

We currently have a phone number on a page, set up so that users on smart devices can tap it and call the number from their devices should they want to get in touch.

My bosses have suggested that, in addition to the number in text format, we should also place a "Call Now" button underneath to make it more obvious to the end user that they can make the call straight from the device.

My gut feeling is that enough smartphone users will be aware that phone numbers are clickable to make this extra button unnecessary - but I can't find much information about this online.

What are people's opinions on this? Is your average smartphone user aware of telephone number hyperlinks? Is there any research available on people making calls direct from website hyperlinks?

Thanks.