Yes. The provided Digiweb modem must be powered on and connected to the Internet at all times for your VoIP service to work. In the event of a loss of electricity / power cut / Broadband supply problem, your Digiweb VoIP phone service will not work. You will not be able to make emergency phone calls.
To avoid loss of service due to a loss of electricity or power cut, you can purchase an Uninterruptible Power Supply (UPS) online or from your local electrical / PC store. A UPS connected to your Digiweb Broadband equipment will provide the necessary power in the event of a loss of electricity or power cut.