Voice over Internet Protocol, also called VoIP or Internet telephony, is the transportation of voice conversations over the internet or through any other IP-based network rather than the public switched telephone network (PSTN).

Protocols which are used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. Some cost savings are due to utilizing a single network to carry voice and data. Users that have existing underutilized network capacity can use VoIP at no additional cost. VoIP to VoIP phone calls on any provider are typically free, while VoIP to PSTN calls generally costs the VoIP user.

There are two types of PSTN to VoIP services: DID (Direct Inward Dialing) and access numbers. DID connects the caller directly to the VoIP user, while access numbers require the caller to input the extension number of the VoIP user. Access numbers are usually charged as a local call to the caller and free to the VoIP user, while DID usually has a monthly fee. One can also find DID that are free to the VoIP user but charge the caller instead.

Key features of VoIP:

VoIP can facilitate tasks that may be more difficult to achieve using traditional networks, such as:
• Routing phone calls over existing data networks to avoid the need for separate voice and data networks.
• Incoming phone calls can be automatically routed to your VoIP phone, regardless of where you are connected to the network. Take your VoIP phone with you on a trip, and receive incoming calls whenever you are connected to the Internet.
• Free phone numbers for use with VoIP are available in the USA, UK and other countries from several organizations.
• Call center agents using VoIP phones can work from anywhere with a sufficiently fast and stable Internet connection.
• Many VoIP packages include PSTN features that most Telcos normally charge extra for, or may be unavailable from your local Telco, such as 3-way calling, call forwarding, automatic redial, and caller ID.
• VoIP allows users to travel anywhere in the world and still make and receive phone calls.

Flexibility:

• VoIP service users can make and receive local phone calls regardless of their location. For example, if a user has a US phone number and is traveling in Europe and someone calls the US phone number, it will ring in Europe. Conversely, if a call is made from Europe to US, it will be treated as a local call. Of course, there must be a connection to the internet, for e.g. Wi-Fi, to make all of this possible.
• Users of Instant Messenger based VoIP services can also travel anywhere in the world and make and receive phone calls.
• VoIP phones can integrate with other services available over the Internet, including video conversation, message or data file exchange, in parallel with the conversation, audio conferencing, managing address books and passing information about whether others (e.g. friends or colleagues) are available online to interested parties.

By: Waqas Taimoor