Change callto: to tel:

[SyncMasta]

Is there a way to change the URL of the phone number from callto: to tel:?

In our case, our CTI software would then be able to interpret this (tel:) and we would dail over it.

[CyberCitizen]

I also had a similar issue, I am now using the following extension in Chrome / Edge.
Allows you to specify what protocol you want to use and works on sites that don't have callto links.

Saves me so much time now.

https://chrome.google.com/webstore/detail/oolkfddhhccdciigjigaghblnlkbgjki