Use your iPhone, iPad, or iPod Touch to make low-cost VoIP calls via SIP client apps like Zoiper and Media5-Fone from the App Store.
Use your Android smartphones or tablets, such as Samsung, Xiaomi, or Google Pixel, to make VoIP calls using apps like Zoiper and 3CX Phone.
Use your Windows desktops, laptops, or tablets to enjoy VoIP communication via softphones like MicroSIP and Zoiper.