With Blizz it is possible to use both, VoIP and telephone on the same meeting. This is ideal when there are restrictions with the internet connection and/or the network is not so good.
To join a Blizz meeting via telephone you just need to use the dial-in numbers, locate your country and enter the meeting ID provided by the Organizer of the meeting.
Blizz offers more than 50 dial-in numbers free of charge. The numbers are available with all the licenses. Here you will find a list with the countries and the numbers accordingly.
Note: Blizz does not charge any fees, please do consider your potential domestic rate costs with your service provider.