Welcome to the RingCentral Community

This is fantastic! Thank you so very much for taking the time to give me such detailed information.

Here is what you need to know about how to transfer a call or to make a call programmatically using RingCentral Call Control API.

1. To transfer a call, you need a phone number to transfer the call. That number can be the number assigned to a physical device as you ask for.

2. To dial a number from a physical phone, you need to have the device id then use the call-out API to dial.

To check the phone number of a physical phone and to detect the device id of a physical phone, you can read the user devices to pick the phone number or the device id required by the APIs mentioned above.

Further readings

https://medium.com/ringcentral-developers/ringcentral-telephony-session-events-notifications-98b3f8d29745

https://developers.ringcentral.com/guide/voice/call-control