During the call, press the 'transfer' button (Button with two telephones) and key in the telephone number.

If you want to announce the caller, just wait until there is contact and hang up after the announcement.

If you don't want to announce the caller, hang up without waiting or pres transfer again.

If you want to go back to the first caller, press the arrows. 2/2 conversations are now shown in the display. By pressing the bottom arrow you can switch between the two calls. Get a hold of it by pressing 'continue'.