Core Features: Support Air and LAN synchronization Seamless handover and roaming Up to 60 base stations Up to 250 handsets Up to 250 SIP accounts Up to 250 parallel calls Support XML/LDAP/Remote Phonebook Support XSI Directory/XSI Call Log External antenna DECT radio coverage up to 50m indoors and 300m outdoors Support Opus Support SRTP / SIPS / TLS, LDAP(s), and HTTPS Support PoE Compatible with Yealink W59R/W56H/W53H, CP930W, & DD Phone