What is SIP and How Does It Work?

SIP (Session Initiation Protocol) is a protocol used in VoIP communications allowing users to make voice and video calls, mostly for free. I’ll keep the definition in this article to something simple and practical. If you want a more technical insight of SIP, read its profile.

Why Use SIP?

SIP allows people around the world to communicate using their computers and mobile devices over the Internet. It is an important part of Internet Telephony and allows you to harness the benefits of VoIP (voice over IP) and have a rich communication experience.

But the most interesting benefit we derive from SIP is the cutting down of communication costs. Calls (voice or video) between SIP users are free, worldwide. There are no boundaries and no restrictive laws or charges. Even the SIP apps and SIP addresses are obtained free.

SIP as a protocol is also very powerful and efficient in many ways. Many organizations use SIP for their internal and external communication, centered around a PBX.

How SIP Works

Practically, here it goes. You get a SIP address, you get a SIP client on your computer of mobile device, plus whatever else is necessary (see the list below). Then you need to configure your SIP client. There are a number of technical stuff to set, but the configuration wizards nowadays make things really easy. Just have your SIP credentials ready and fill the fields whenever required and you will be set in a minute.

What is Required?

If you want to communicate through SIP, you need the following:

  • A SIP address/account. This is obtained free from many providers. Just register online; you can have yours now for free. Here are links to help you get a free SIP account.
    – What is a SIP Address? 
    – Providers of Free SIP Addresses
    – Registering for a SIP Address
  • A SIP client. This is a program that you install on your computer or mobile device. It contains softphone functionality and some other features and provides an interface for you to communicate. There are different types of SIP clients. Among the most common ones are the applications offered free by VoIP service providers, to use with their VoIP services. Some of them support SIP. But you have clients that are built for SIP and do not depend on any service. You can use them with any SIP account, and can even use them within a PBX environment. Here is a list of the most popular free SIP clients on the market., and here is how to configure a SIP client.
  • An Internet connection. With sufficient bandwidth for voice and video communication. Not much is required for voice communication, especially if you are using enhanced codecs for low bandwidth consumption, but you need solid bandwidth for video communication. You will prefer a DSL connection.
  • Hearing and talking devices. You need what it takes to get your voice through and to hear what is being said, and what is being presented in images. A headset, earpieces, a microphone and a web cam for video communication.
  • Buddies to talk to. Maybe this is the first item in the list that’s checked. You may have buddies, but they need to be using SIP too, if you want the calls to be free. Share the SIP addresses just like you do phone numbers.

How About Skype and The Other VoIP Providers?

VoIP is a wide and expanding industry. SIP is part of it, a building block (and a strong one) in the structure, possibly one of the pillars of VoIP. But along with SIP, there are a number of other signaling protocols used for voice and video communication on IP networks. For instance, Skype uses its own P2P architecture, as do some other service providers.

But luckily most VoIP service providers support SIP both in their services (that is, they give you SIP addresses) and the VoIP client apps they offer to be used with their services.

Although Skype does offer SIP functions, you will want to try some other service and client for SIP, since what Skype proposes is paid and intended for businesses. There are so many SIP address providers and SIP clients out there that you won’t need Skype for SIP communication. Just check on their web sites, if they do support it, they’ll make it a must to tell you.

So, go ahead and take a SIP.

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