Each 5100 Call Server can support up to 500 IP or analogue extensions and is supplied as standard with 4-16 voicemail ports and 1,500 hours of voicemail storage. Basic Auto Attendant is also included. Constructed on a Linux platform and built around an LDAP database, the 5100 Call Server module provides the foundation of the maximiser system, hosting call routing capabilities, voice processing, a SIP Proxy Server, H.323 Gateway & GateKeeper and integral Apache Web Server.