You will need to have the Video Gateway add-on for this feature to be activated. 

To join a SimplyVideo call using a videophone, click on the link provided by the meeting host and click 'Phone Device' under 'More ways to join'.




Then follow the prompts to select the country you are dialling from to get the correct dial information.

Dial the local rate number
Enter the Conference ID
Enter a PIN, if prompted to do so.

That's all there is to it!