What are VOIP and SIP Protocols and how do they work?

VOIP & SIP protocols


What is VoIP?

VoIP (Voice over Internet Protocol) also called IP communication framework as it gives

the telephone benefits over the internet. With a decent internet connection, it can give

telephone benefit conveyed through the internet connection rather than nearby telephone

organization. It transmits voice and mixed media content on internet protocol. It is the

combination of advancement and methods use to transmit call over the IP. It can be

deployed on LAN and WAN.

Why VoIP?

The two main objectives to use VOIP

1- Economic

2- Increased Functionality


Basically, VoIP lines cost less than the traditional PSTN lines provided by different service providers. In traditional PBX system additional cost is paid for the service and the cost increases as the features are added into the PBX system and the PBX is managed and configured by the specific company engineers, while in VoIP PBX system for instance Asterisk VoIP PBX system, it is free and it can be installed on the simple PC and can be managed and administrate by the user itself and are enrich in featuresas compare to the traditional PBX.

The call over internet protocols are free but user have to pay for their internet connection.

Also, there are service packages for calling on PSTN and GSM from VoIP which are way

cost saving and cheap as compared to the charges of the PSTN or GSM service providers.

There are many services which supports this technology like free calling for example

Skype, WhatsApp and Free world dialup.

Increased Functionality:

VOIP make thing easier as on your fingertips which

are almost impossible in traditional phone networks.

Calls can be routed directly to the desired VOIP phone. Most important feature is that it

provides you a new level of mobility in case of PBX systems. User can carry its phone

anywhere and can communicate.

It is very beneficial for the call center agents as they can communicate form anywhere

and can provide service and assistance from almost anywhere.

How VoIP works?

The basic concept behind VoIP technique is

  1. First of all it continuously sample the audio.
  2. Each sample is converted into digital form.
  3. Then the digital stream is sent to the IP network in the form of packets.
  4. These packets are converted back into the audio stream for the playback.
  5. Before the procedure above, the system must handle call setup. Phone number to IP.

Routing Protocol:

Just like every call system require some protocols to follow for signaling and call handling

for example, SS7 (Signaling system 7) is used in PSTN network, SIP (Session Initiation

Protocol) is used in VoIP network for signaling and call establishment and handling.

What is SIP?

Session Initiate Protocol, its SIP base. The SIP Channel Segment enables Asterisk to

connect by mean of VOIP with SIP phones and exchanges. Asterisk is able to act as a SIP

client. Taste is an extremely adaptable convention that has awesome profundity. It was

intended to be a universally useful approach to set up continuous mixed media sessions

between gatherings of members. For instance, notwithstanding basic phone calls, SIP can

likewise, be utilized to set up video and sound multicast gatherings, or texting meetings.

In this report, we’ll concentrate on SIP’s capacities for VoIP, and how it sets up calls that

at that point utilize RTP (the Real-time Transport Protocol) to really send the voice

information between telephones. Asterisk goes about as a Media passage between SIP,

IAX, MGCP, H.323 and PSTN affiliations. For instance, an Asterisk server can be

connected with ISDN to give your SIP customers availability to the exchanged

correspondence deal with.

SIP Methods:

Like in SS7 there are messages like IAM, ANM, and REL etc. there are six basic messages

types of SIP known as methods which are used for the establishing and handling the call.

Method Purpose

INVITE A request is sent to the other user for call initiation

ACK The requested user responds the request for session initiation

BYE Session terminated

CANCEL Cancel the pending requests

REGISTER It registers the location of the user

OPTIONS It determines the capabilities of the end user.


Other Protocols:

There are also other protocols except SIP for routing and call management and converting

information form one form to another such as IAX AND DAHDI but we will discuss it in layer articles at knowledge-bull.com


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