CallPad 2.0.1 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. CallPad for Mac relates to System Tools. We recommend checking the downloaded files with any free antivirus. This software for Mac OS X is a product of Appersian.
From the developer:
CallPad is a very simple app to ease making phone calls without picking up your iPhone in OS X Yosemite. CallPad requires an iPhone with iOS 8 and an activated carrier plan. Phone calling works with any iOS device that supports iOS 8 and any Mac that supports Yosemite.
You may want to check out more Mac applications, such as ImTOO iPhone Transfer, Xilisoft iPhone Transfer or RAGE SEKeyword, which might be related to CallPad.