2 line cordless business phone - ?

We spent a few thousand dollars a couple of years ago on a cordless phone package from HWN in Markham. Called the Airway cordless phone.
Looked promising at first and their site mentions large companies such as Pittsburgh Paint, UPS, AT&T as users of their phone systems.

Am not happy with their phones and even unhappier with the company's service. Does anyone know of any other cordless 2 line phone systems for a small warehouse environment?
Have tried RCA and Panasonic and need something a little more durable.

Thanks in advance.