An IP Phone (Avaya, Cisco), also called a VoIP Phone, is a phone with built in software that allows it to connect to a network. Instead of connecting to your phone line, it connects directly to the internet. IP phones take advantage of the many features available on VoIP networks that are not possible on traditional phone lines. IP Phones have more in common with smartphones than they do with older phones, and some are so powerful they can even run apps.
The IP phone is designed to work within the VoIP (Voice over IP) environment. In essence, the IP phone allows you to make telephone calls over the IP network, converging voice and data over the same connection as an alternative to the standard PSTN. Calls made on an IP phone traverse the Internet, or the private IP network of a particular company.
To operate effectively, IP phones rely on protocols such as SIP (session initiation protocol), SCCP (Skinny Client Control Protocol) or any other of various proprietary protocols. The IP phone can be as simple as a software-based softphone, or as complex as a purpose-built hardware device that will appear to look like an ordinary telephone or a cordless phone. When an analog telephone adapter is in place, the ordinary PSTN phone can be used as an IP phone.
There are specific elements that make up the IP phone, including the physical hardware, the STUN client, the DHCP client, the DNS client, the signaling stack, the RTP stack and codecs, including audio and video where appropriate.
The common features of the IP phone include caller ID; dialing using name or ID – this capability differs from speed dial as no number is actually stored on the client; locally-stored and network-based directories; conference and multi-party call; call park; preserving user name and number; applications; and call transfer and hold.
While the IP phone does require Internet access to make calls outside of the local area network (LAN), a compatible local PBX can be made available to handle calls to and from outside lines in the event the VoIP platform is not available. IP phones also depend on electricity for operation, but any risk of power outage can be mitigated with the installation of a UPS.
