IP Telephone Set
Looks like a telephone instrument but is essentially a Local Area Network (LAN) device which requires an IP address from your network switch. Some IP Telephones has an embedded network switch which will allow you to run both Voice and Data on a single cable infrastructure - known as a converged network. An alternative would be to run a separate LAN with separate cabling and a network switch. These phones do require Power which can either be provided by the network switch, or through a local power adapter per phone.
Typically, IP Telephones require an IP license (from the PBX vendor) and IP address (from the LAN) instead of a port to function. An IP Telephone is also referred to as VoIP Telephone. An example of a VoIP phone is as follows:
Digital Telephone Set
This fancy phone is proprietary to the PBX make and model and therefore cannot be used on other PBX providers systems as may be the case with IP Telephones. Various function levels are usually provider, with high-end Digital phones having an LCD Display, soft keys for call appearance and one-touch functions to name a few. These handsets will also display caller ID as long as this is sent by the network. Digital phones are much more feature-rich and functional than an analogue telephone instrument. An example of a Digital Telephone is as follows:
Analogue Telephone Set
Also termed SLT (single-line telephone) has been the most common telephone instrument for business use. Analogue phones only require two wires with an RJ11 connector clip to connect to the PBX network or Analogue line (PSTN). Some have basic LCD to display time, digits dialed and ‘half-duplex’ hands free function. An example of an Analogue telephone is as follows:
Key Telephone Set
Telephone with several buttons used for call hold, line pick-up, auto-dial, intercom and other functions. Key sets are older technology which is seldom used in the PBX environment.