VoIP Interview Questions with answers

VoIP Interview Questions with answers:


What is VoIP?

VoIP stands for Voice over Internet Protocol. It means the transmission of voice and call control data over the Internet. In other words, this technology allows you to make phone calls over the Internet.

How does VoIP work?

To understand how VoIP works, you will be taken through the process of voice transmission from one end to the other. The process starts with a person talking into the mouthpiece on one end of a VoIP call.

This analog voice signal must first be sampled and digitized. Voice sampling is usually done 8,000 times per second (8KHz). In order to reduce bandwidth, a voice CODEC is used. A voice CODEC is a compression/decompression algorithm that is optimized for the voice frequency range. The bit stream uncompressed is 64Kbps. By using an available CODEC, the bit stream can be reduced to 8Kbps or less.

In order for the compressed voice data to be sent over the Internet, it must go through a process called packetization. This is a packet consisting of a small sample of the voice data (usually 10-30 milliseconds).

While being routed through the Internet, these packets can get delayed or even lost. This can cause degradation in voice quality. Simply put, there are various mechanisms in place to compensate for these problems and help smooth out the audio.

Once all the packets arrive on the listening end of the call, they must be reassembled to their original state. The packets are decompressed and converted from a digital to analog voice signal.

What equipments are needed for VoIP?

Generally following things are required for voip

  1. Broadband connection
  2. voip phone
  3. nexton softswitches
  4. router
  5. audiocodec
  6. astric server

What are the advantages to VoIP?

The big advantage is VoIP may save you money depending on how much you are currently spending for local and long-distance calls. What you will need to do is get the total cost the phone company is charging and compare it against a VoIP plan that interests you. With most plans, you get free calls within the U.S. and Canada for a low flat rate. International calls usually have very low rates with no connection fees. For both residential customers and businesses that make a lot of long distance and international calls, the savings can be several hundred dollars a year.

Another advantage is with the features available with VoIP. Features such as caller ID, call waiting, call forwarding, 3 way conferencing and voice mail are usually included at no extra cost. With the phone company, these services are usually extra.

In addition, you can make free phone calls anywhere there is a high speed Internet connection available. That means you can be in another state or even in another country and make calls as if you were back at your home or business. You will just need to bring your phone adapter along with you and possibly a phone in case one is not available.

What do internet telephony,packet telephony,IP telephony and converged network means?

The first thing all mean the same thing. Which is using IP (Internet protocol) for voice services. Some voice networks are only packet-switched and have no access outside of their own VoIP network. Most VoIP networks have a Gateway that connects to a circuit-switched external network which gives them acces to external calling. One of the gateways responsibilites is to convert G.711 Circuit-switched media (typically a T1 provided by a telco company) to the 7.723 Packet-switched media that will traverse the companies VoIP network. A device called a gatekeeper will then convert the IP address (used by H.323 protocol) to a standard telephone number (E.164 address) that can be used for external calling.

A converged network is a network that passes both Voice and Data over the same set of devices. Converged networks generally implement QoS (Quality of service) on all actived network devices to ensure the VoIP has priority over standard data because of it's more rigid demands.

What Are Some disadvantages of VoIP?

If you're considering replacing your traditional telephone service with VoIP, there are some possible differences:

  • Some VoIP services don't work during power outages and the service provider may not offer backup power.
  • Not all VoIP services connect directly to emergency services through 9-1-1.
  • VoIP providers may or may not offer directory assistance/white page listings.