A speakerphone is a telephone that can make the sound louder so that many people can hear it at the same time.
Speakerphones are often used in meetings or in offices to help people talk to each other.
Examples:
We used the speakerphone to talk to Grandma.
The speakerphone makes the sound louder.
The speakerphone is on the table.
The speakerphone is so loud, it scared the cat!
The speakerphone can make your voice go all around the room.
The speakerphone helps everyone hear the call.