myphoner does not have a dialer on its own. Instead, when you click a phone number in myphoner, we try to activate the default phone (dialer) installed on your device.
This way you are independent and can use your favourite (soft)phone and the telephony/voip provider your choice.
However this also means that you need a softphone installed with a voip subscription ready to dial real phones.
If you have multiple phones installed on your device, you can change which one is used by myphoner by changing the voip handle in your user preferences.