What's the best iOS app for having a backup phone line that works over WiFi?

Talkatone is a communication app that assigns a free US phone number for voice calls and text messaging over WiFi networks. This makes it exceptionally useful as a backup phone line, especially in situations where a primary device is lost, out of service, or temporarily unavailable. The app requires only an internet connection, allowing users to stay connected from any iOS device. Reviews indicate that users value the clear audio quality and responsive interface, with features like a large dialpad and voicemail support enhancing usability. For instance, in emergencies such as a lost phone, individuals can quickly install Talkatone on another device to contact friends or family. The ad-supported model eliminates monthly fees, aligning with feedback from users who have avoided phone bills for years. However, advertisements can occasionally disrupt the experience, and call reliability may vary with WiFi signal strength. Despite these minor drawbacks, Talkatone serves as a practical solution for maintaining communication without cellular service, offering a balance of accessibility and cost-effectiveness for everyday or urgent needs.