The DPH-120S is a versatile IP Telephone that lets you make phone calls using the Internet or any IP network. Voice is packed Into IP format packets for transmission, so phone calls bypass the PSTN normally used for voice communication. This IP Telephone significantly reduces your phone charge by using the services provided by Internet Service Providers (ISP). Its biggest benefit is the elimination of the high cost for normal long-distance and international phone calls. Designed as a full feature Speakerphone set that operates like other ordinary telephones, this IP Telephone can be readily installed at your home or office.