Used Spectralink phones 

The Spectralink 6020 wireless telephone is the industry’s most reliable handset for the workplace. Only Spectralink combines innovative design with advanced manufacturing and test processes to ensure handset durability. The rugged one-piece style has no moving parts or external antennae, so there is certainly nothing to break or come loose. Spectralink wireless telephones seamlessly integrate having a variety of host telephone systems to supply advanced calling attributes throughout the workplace.
http://www.synergy-tel.com/spectralink/spectralink-6020-dual-charger-bundle/