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