In order to make and receive calls, you need to have the following things with you. Only after this, you can run the process smoothly. First of all, there are 3 things that are primarily required for connection: The phone, Echo device and VoIP with Alexa app installed on the phone. The phone app will be used to sync the contacts with Alexa through Echo device. After this, when you command Alexa to call anybody who is saved in the contact list. It will automatically arrange a call for you.
Amazon Echo Controller | Amazon Echo Support | Connect Amazon Echo To Bluetooth Speaker