High Quality Content by WIKIPEDIA articles! The Avaya Aura Application Server 5300 or Avaya Aura AS5300 in telecommunication and computer networking is a secure Unified Communications (UC) system designed and manufactured by Avaya. The system provides integrated IP telephony, conferencing, voice mail and instant messaging - all centered around dynamic presence - that meets, US Department of Defense (DoD) and US federal government security and service assurance requirements. The AS5300 is used for creating, modifying, and terminating two-party (unicast) or multiparty (multicast) media streams, supporting up to 25,000 subscribers per system.