VoIP Phones
VoIP Phone Overview
The VoIP phones use IP technology for making call over IP network such as Internet. The VoIP phones can be corded phones or cordless phones. The VoIP phone though looks similar to normal phone is functionally the same but technically different. In addition to normal phone components it has a DSP (digital signal processor) engine for converting of voice signals to digital signals and an Ethernet interface for connecting to LAN network. The VoIP phone is connected to Ethernet network using RJ45 patch cord as against to telephone lines in case of normal telephones. The VoIP phones uses protocols like SIP (Session initiation protocol), H323, Skinny, Skype etc.
The VoIP phone communicates through VoIP gateway for making calls. The VoIP gateway routes the signals through the IP network for destination. The calls to landline network using VoIP are converted into suitable format by VoIP gateway which connects to the traditional telephone lines taken from telephone service provider. These phones are also used in IP PBX for making calls. The IP PBX has building gateway and other functionality to support these phones.
The VoIP phone being connected to Internet can also provide additional features such as weather reports, news etc.
VoIP Phone Features
The VoIP phones like traditional phone come in variety of features such as:
- Caller ID
- Multiples Call waiting with display of called party’s identity.
- Phone directory
- Speakerphones with Volume control
- Built-in WAN/LAN interface
- Hearing Aid Compatibility
- Backlit large LCD display
- Conferencing
- Call Forwarding
- Intercom function
- Call Transfer
- Customizable Keys,
- Redial
- Hold
- Mute
- AC Adapter
- RJ9 Headset Connector interface
Some phone provide Integrated IEEE 802.3af Power over Ethernet (PoE) support for taking power from the switch to which the phone is connected over Ethernet (LAN) interface. Some phones have built-in 2 port Ethernet switch so that PC can be connected to the phones.
Some cordless VoIP phones work with a base (Such as VTECH IP8100), which has built-in router for WAN interface. These phones can be directly connected to Internet. Some phones have special application layer gateway configured to allow a VPN connection to pass through a NAT router. This allows the system call from VPN system to be made and received.
The VoIP phones depend on the Internet connection for making calls and the quality of call depends on the quality of Internet connection.
