Avaya 5620SW IP Telephone (700339815). The standards-based Avaya 5620SW, developed specifically to meet the needs of small and medium businesses, bring rich features and functions directly to the desktop, while also supporting desktop applications above and beyond telephony. The Avaya 5620SW IP Telephone is an entry-level voip phone and is built specifically for demanding call center center environments. The 5620SW IP telephones are for use with the Avaya IP Office system.