Yealink is a growing brand, popular for their open-source IP phones that are both powerful and reliable. Yealink phones come in a variety of models, some Gigabit and some fast Ethernet; however, they certainly have a phone that will satisfy you and your businesses' needs. Yealink devices are great for open source software like Asterisk, or even Vonage users, SIP and VoIP systems.
Dotcom Computers sells both new and refurbished Yealink IP phones. All phones include a one year warranty against defect.