If you use a VOIP system that require the use of Tel links follow the instructions below to set this up on your PC or MAc
How to Set Defaults for Tel Links on a PC
1. Settings > Apps > Default Apps.
2. Select Choose default apps by protocol.
Under TEL URL:tel, click on the current entry (blank or another assigned application) and select the app required.
Selecting Your Default Application for Opening Telephone Links on a MAC:
1. Open and sign in to FaceTime.
2. In the menu bar at the top of your Mac's screen, click the FaceTime drop-down.
3. Click preferences.
4. In the drop down for “Default for calls,” select the required app