RingCentral is a VoIP communications service that allows you to make phone calls over an internet connection.VTiger CRM is a full-featured, open-source CRM application that provides customer portal, Outlook plug-in, and reporting features.RingCentral works by combining business calls, messaging, and other communications over your existing local internet network.RingCentral is a cloud-based communications app that offers phone, text, voicemail, team communications, and document sharing on one platform.