IP telephony is used in internal PBX systems for businesses, Call Centers, unified communications tools and applications even in households.
Often using the phone, people always think that it will cost you money to feed them every day. But this is also the difference that the ip phone line brings is "cost savings". You can call your colleague and company for free.
Moreover, the IP phone has its own Dect lines that support you to move anywhere in the office and does not affect the quality of the call. The simple thing is that you only need to be connected to the internal LAN to be able to talk.