I need to have a mobile device dial the phone number of the id (button) through bluetooh, what do you recommend?
If the PC and the phone are connected to the same network then it will be simpler to use MQTT.
I'm looking at the example that you have reported me and I'll see to study it, but in that case I have to create an app for the device that is listening and with b4j that makes forward the comenado.What is the question? You should use AsyncStreams to send anything you like to the phone and then send the SMS message from the phone.
Important example: [B4X] Network + AsyncStreams + B4XSerializator
I wouldn't use Bluetooth for this unless there is no other option.