The latest versions of MiCollab have added this ability by default for tel and callto links. I think your version should have this.
In chrome you may have to modify C:\Users\YourUser\AppData\Local\Google\Chrome\User Data\Default and edit the Preferences file. I think I did this as a test for someone as I can invoke the dialer with tel and callto
You need to find "protocol_handler", I think there are 2 occurances and after the second you can see the format, but I think mine has both "tel":false, and "callto":false,
I did make a bat file that searched this "protocol_handler":{"excluded_schemes":{"afp":true, and replaced it with "protocol_handler":{"excluded_schemes":{"afp":true,"tel":false, "callto":false,
Seems chrome it will reorder it alphabetically :-)
This should give some guidance.