telephones
The telephone is the electrical system of communication that you use to talk directly to someone else in a different place. You use the telephone by dialling a number on a piece of equipment and speaking into it.
phone
It's easier to reach her by telephone than by email.
打电话比发电子邮件更容易联系上她。
I hate to think what our telephone bill is going to be.
我不愿去想我们的电话费会有多少。
A telephone is the piece of equipment that you use when you talk to someone by telephone.
phone
He got up and answered the telephone.
他站起来接了电话。
on the telephone
If you are on the telephone, you are speaking to someone by telephone.
Linda remained on the telephone to the police for three hours.
琳达和警察通了3个小时的电话。
telephones , telephoning , telephoned