VoIP stands for Voice over Internet Protocol, or a means to digitally transmit voice calls over an IP network instead of using traditional analog phone lines. In most cases, business VoIP service uses a broadband Internet connection and specially-configured VoIP phones to place and receive calls.
PBX stands for Private Branch Exchange, and generally refers to a business phone system. A PBX system is generally designed with special features to handle internal call switching, such as transferring a caller to another extension or conferencing in a 3rd party within the same office.
VoIP PBX is a special class of PBX systems that uses voice over IP service to place and receive calls using the Internet. This service is frequently hosted from remote by the 3rd party VoIP provider, in which case it may also be referred to as a hosted VoIP PBX.
A VoIP phone is a specially-configured phone that places and receives calls over the Internet instead of over traditional analog phone lines. When used as a call center VoIP solution, the PBX-integrated phone features of a VoIP phone can increase employee efficiency and help project a professional image. These features can include call transfer, conferencing, call hold, and much more.
SIP stands for Session Initiation Protocol, a standard protocol used to transmit voice data over the Internet with a VoIP phone. The servers used by VoIP service providers are commonly referred to as SIP servers, and the phones used by hosted VoIP PBX users are commonly referred to as SIP phones.
e911, or enhanced 911, is a telecommunications system that pairs a phone number with a physical address for the purpose of directing emergency dispatch calls to the nearest Public Safety Answering Point (PSAP). Since VoIP phones and phone numbers are not tied to a physical address, VoIP solutions require that users register and update the location of each phone. Failure to register alternate addresses with Gateway Telnet may result in any VoIP phones that are located at these sites incurring additional charges when 911 calls are made from these non-registered locations.