Yes, the connection cable is included with the Doro PhoneEasy 312cs. The package includes a telephone with curly cord, a telephone line cable and other accessories.
Hello digitec_wba
On the Doro PhoneEasy website you will find a manual for the phone.
Enclosed is the link: https://www.doro.ch/fileuploader/download/download/?d=0&file=custom%2Fupload%2FManual_Doro_PhoneEasy_312cs_DE_v10.pdf
On page 2 you can see all the function keys of the phone. In my opinion, the volume control is located under the handset, as a small rotary dial.
Greez
whitelemur