Some telephones, depending on the brand and model, have the intercom function, which allows to begin communication by sending the signal. When the signal comes, the telephone set rings a signal different from the standard ring tone call. After that the telephone temporarily switches off from the telephone line and works as an intercom.
ShoreTel Sky is the modern phone system for today’s agile, mobile and always-on company. While other cloud-communications companies have added business VoIP services as an afterthought, hosted VoIP is the heart of ShoreTel Sky.