What is the difference in call initiation for desk phones and Web Phone instances in Google Chrome?

Difference in call initiation for desk phones and Web Phone instances in Google Chrome

If using a desk phone, clicking on the "click to dial" feature will ring your desk phone, and you must answer before the dialing begins. If logged into a Web Phone instance on your Google Chrome browser, the call will be initiated directly, and you must accept the call to start the conversation.