For use cases where one wants to track calls, length or connection, the better way to do this is the click-to-call approach. Have a button that says, "Call Me"

For use cases where one wants to track calls, length or connection, the better way to do this is the click-to-call approach. Have a button that says, "Call Me". If you have the user's number place a call to them and connect it to the destination number. If you don't have the user's number then collect it before placing the call. There are much better tracking benefits and data collection for phone numbers. If one is doing marketing and wants a person to call, there usually isn't much of a difference in conversion rate between a call to action like "Call 800-555-1212" and a form that will call you. Source: An employer powered a metric shit-ton of advocacy call campaigns - like the STOP SOPA & PIPA stuff that took over the internet a few years ago.