DAG1000-4S is a multi-functional analog telephone adapter which offers seamless connectivity between IP-based telephony networks and legacy telephones (POTS), fax machines and PBX systems. With standard SIP protocol, it's compatible with leading IMS/NGN platforms and SIP-based IP telephony systems. It provides 4 FXS ports, fax over IP and flexible dial plans. Offering high-quality and reliable voice-over-IP service, the device is ideal for call centers, small and medium enterprises, SOHO and residential users.