On the other hand, your call quality on VoIP will be affected by the state of your broadband line - slow internet can mean rubbish phone calls. As long as you can sign in on the app, your contacts can call you. One of the most important correctable issues would be to check for double NAT. Ethernet vs. VoIP calling app-to-app is almost always free; calling a landline or mobile number may cost a little; and other VoIP services, including those from Hyperoptic or business providers, require a monthly fee.
VoIP: The complete beginner’s guide