Log into the web interface under the DL that you want to use. Then go to Call Handling & Forwarding and add the number, but leave the switch turned off. See image below. Then when you log back into the Softhpone, you should see it in the dropdown.
This reply was created from a merged topic originally titled Desktop app: dial on Softphone but talk on Deskphone phone?. If you want make a call from the hardware VoIP phone but want to dial from the Desktop App (because it's just one convenient click)
how can you do that in RC?
We have a number of users who make lots of outbound calls and it's tedious to type numbers from the desktop screen into the hardware phone. There must be a way to make the VoIP dial from the desktop app!