Does a conference room speaker exist for cell phones?

I'm looking for a product that I'm not sure exists. I guess there are conference room speaker systems with a microphone attached that allows for everyone to be heard well over a speaker during a meeting. (Hopefully this is the correct description).
Does anyone know if an item like this exists that can be used with cell phones, or cell phones AND landline phones? And, does anyone know the proper name for an item like this?
Thank you!

Like videoconferencing, boardrooms also have audioconferencing capability through telephone lines. There is a device to which the room's audio equipment feeds into the phone to transmit to the remote location, and also feeds the remote location into the room's audio system. Each end needs one of these interfaces, and they're designed so that each end can hear the other without their own speaking feeding back into their own sound system.

Since they use the RJ11 telephone cables to attach the telephone to the interface, I don't think there is anything like that for cell phones yet. But there may be. I'm just not aware of it.

Many cell phones have a speaker phone option but that will not work as well as a real speaker phone. Most speaker phones use a regular analog phone line and they do work very well. Polycom makes great speaker phones:

http://store.polycom.com/

If you really need a call to be heard in a conference room with a group of people, then it is worth it to get a good speaker phone (sometimes they are called a conference phone).

on my old phone i had a thing called conference call

it is called speaker phone