The term 'PART OF AN OLD TELEPHONE' can be broken down into two crossword solutions: HANDSET (7 letters) and CRANK (5 letters). A HANDSET is the part of a telephone that is held in the hand and contains the speaker and microphone. It is connected to the base of the phone by a cord. A CRANK was a feature of old telephones that allowed the user to generate electricity to power the phone. The user would turn the CRANK to generate the electricity, which would then power the phone.