SIP calling explained: cutting through the jargon

For a layperson, phone systems might seem to be so straightforward.

You pick up a handset, dial a phone number, and you are talking to anyone in any corner of the world.

But what they don’t see are the huge lengths of copper cabling that lie underneath making the connectivity possible. Or the hours of manual installation time required to get those systems up and running. This was the case with analog or on-premise phones. You might better know and recognize them as rotary phones or dial-pad phones. 

As technology has developed, we’ve seen new technology and therefore new terminology appears faster than anyone can keep up — and Session Initiation Protocol (SIP) calling is just one of many. But it’s important to understand the differences between types of phone systems so that you can choose the setup that’s right for you.

You might have an idea of the benefits that internet-based telephony has to offer. And with communication being an essential factor for the success of small businesses and enterprises alike, it could be one of the most important decisions you’ll make.

Help is at hand, as we’re going to use this blog post to explain it all. We’ll be taking you through:

  • What SIP calling is
  • How SIP calls work
  • The benefits of the system
  • Who uses it today
  • The main differences between VoIP and SIP calling

So that when all is said and done, you can be fully informed and ready to go with all the information you need for your business.

Let’s get started.

What is SIP calling?

Session Initiation Protocol (SIP) is essentially a set of rules that allows two systems to exchange information over a network such as an internet connection. That information can take a number of different forms, allowing for many practical data uses. In SIP calling—you guessed it—that’s generally the form of a phone or video conversation.

By allowing you to start and stop those information exchanges, SIP essentially allows internet calling to be carried out cheaply, quickly, and securely. Opening up the possibility of making voice calls, video calls, and so much more from any device including Android and iOS smartphones.

Breaking down the terms associated with SIP calling

To dig a bit deeper into what SIP calling really means, we need to unpack the terms that make it up. Here goes.

‘Session’ is fairly straightforward. This simply refers to the period of time during which data and instructions are exchanged by two devices. In telecommunication, this is also sometimes referred to as ‘signaling’.

‘Initiation’ is also easy to understand. The act of starting a session, but also maintaining and ending it. Which gives SIP the ability to open and close connections.

‘Protocol’ is a term used across computing, and typically translates as a set of rules that govern interactions between devices. By creating a predefined structure for communication, it ensures that those devices are speaking the same language, and can understand each other clearly.

Put it all together and you’ve got a protocol that allows computers, deskphones, and mobile phones to connect with voice calls, video calls, or instant messages. So that clear conversations can be held over an internet connection.

So, how does a SIP call work?

SIP calling means cutting out the middleman when it comes to connecting your business to the rest of the world. At the same time, it takes advantage of the vast capacity of your existing internet connection – be it a home Wi-fi or enterprise broadband connection. One of its greatest benefits is that it allows you to connect to older, hard-wired numbers, and to directly upgrade your existing system without needing to start from scratch.

In a traditional phone system, it might feel like you can just plug in a handset and start calling anyone in the world. But there’s a lot more than that going on under the hood. In an analog or on-premise phone system setup, you’ll tend to find three main parts that together provide your connection.

  • Private Branch Exchange (PBX). This is an on-premise system made up of PBX boxes and central server systems that are physically installed at your offices. It’s this PBX that your phone hardware directly connects to in order to make telephone calls.
  • Primary Rate Interface (PRI) lines. These are physical cable connections that link your on-premise PBX to the external PSTN. That is to say, the physical connection between your offices and the outside world.
  • Public Switched Telephone Network (PSTN). This is the external, public telephone network that takes care of routing calls to your intended recipient.

Where SIP is installed as an upgrade to an existing system, the PRI lines are rendered redundant. Instead, a SIP trunk (effectively a digital phone line) is installed virtually. It uses the internet to create a direct link from your PBX to the PSTN, removing the need for long lengths of copper cabling, and providing all the benefits of an advanced internet-enabled network.

For those installing a brand new system, the only hardware you’ll need to purchase are any handsets you wish to use, on top of your existing internet connection.

The SIP protocol itself runs a series of automated checks during the call. It confirms that the recipient is in an accessible location (i.e., with network coverage) and that their status is set as available to respond. It also checks that the recipient’s device is compatible with the desired type of call (i.e. it has a camera if you’re attempting a video call), and initiates the call. It maintains and then ultimately terminates the connection when either party hangs up.

In effect, however you go about upgrading to unified communication, this unlocks a raft of advanced features and functions for your system.

The benefits of SIP calling

Unsurprisingly, SIP calling unlocks several clear benefits to businesses operating in a fast-changing world. With customers who want to reach them in increasingly diverse ways, and with the remote working revolution transforming the employment landscape, SIP calling can turn around telecommunication for your business.

Here are some of the top benefits:

  • Easily scalable

SIP systems communicate entirely over the internet, and modern fiber optic cables have a vastly greater data capacity than old-fashioned copper lines. Once you’ve upgraded to a fully cloud-based system, it exists virtually, so scaling up for a growing business comes at little more than the click of a button. 

And with most SIP providers offering flexible billing, you can simply upgrade your plan to accommodate additional agent licenses or increasing call volumes. Long gone are the days of arranging manual installs for every new line, and reprogramming every phone line with additional extensions.

  • Vastly flexible

SIP calls can be received on all kinds of mobile and laptop devices, allowing employees to access the telephone system wherever they are in the world. Even if you have multiple numbers that you can be reached on, you can use the same device — be it an analog desk phone or VoIP softphone to pick up or place calls no matter which number is being called. The ease with which staff members can mark themselves as offline provides a clear and welcome distinction between work and leisure hours. 

It also ensures calls are routed to the most relevant—and available—agent. This facilitates flexible working that operates around your business, thanks to the availability of high-quality calls wherever your employees need to be.

  • A smooth transition

SIP trunking allows you to upgrade your existing telephone system to an internet-based setup without making your existing kit redundant. So if your workforce is too familiar with their existing phone system, you can still take advantage of cheaper running costs and telephony upgrades without upsetting their workflow.

  • Cost-effectiveness

The flexibility of subscription plans for SIP calling means you’ll only pay for what you use. And with clear pricing models, you’ll know exactly what the telephone system will cost you to run on a monthly, quarterly, or even annual basis. Not to mention the saved expenditure on installation and system maintenance costs.

  • Built-in redundancy for greater reliability

On-premise, hard-wired systems rely on your business’s self-owned PBX and localized hardware. As with any hardware-reliant technology, all of these components can go wrong, and when that happens, not only does your entire phone system go down, but it’s also up to you to fix it. That means time, that means expense, and that means lost revenue for your business. 

When you move to a cloud-based system or a VoIP service, responsibility for your phone network’s up-time falls on your service provider, and with redundancy built-in to SIP server network systems, the chance of total failure is drastically reduced. So you can keep on working with a reliable business communications operation.

  • Advanced integrations with cloud-based telephony

If you go for a fully integrated model, your entire suite of communications—internal and external—can be combined into one easy-to-use, computer-based system. Your phone system can connect directly to your Customer Resource Management (CRM) software, which allows you to keep clear records of your business’s relationships. Furthermore, SIP calling also lets you handle VoIP calls over mobile apps which just unleashes productivity for your workforce.

As customers look to contact companies across email, social media, real-time chat, as well as by telephone calls, omnichannel functionality can bring all of these together in one place. That saves your employees huge amounts of time from switching between different business communications software for video conferencing, VoIP calls, or instant messaging allowing them to spend more time speaking to customers and advancing your business.

Who can use SIP calling?

Companies all over the world, in every sector imaginable, are upgrading their phone systems. Enjoying the benefits of faster, easier, and more flexible collaboration through video conferencing, voice calls, and instant messaging.

Whether they’re drawn in by the ability to connect with employees and customers wherever they might be, the long-term cost savings of switching, or the flexibility and scalability offered by the service and its accessibility across laptop and mobile devices, there’s been a clear trend of adoption for a sustained number of years.

It won’t be long before the question is no longer “should you switch?”, but “why haven’t you switched yet?”.

The difference between VoIP and SIP 

If you’ve heard of SIP, you’ve almost certainly come across VoIP as well. Rather than being rival technologies, it’s best to think of them as different tools that work together towards the same end goal.

Voice over Internet Protocol (VoIP) is the basic translation technology that allows audio to be transmitted and connected over the internet. As the original technological breakthrough that began the wider revolution, it underpins all of the internet telephony, including SIP.

SIP protocol works hand in hand with VoIP to maintain the connection between those devices, together making internet calling easy and affordable. Crucially, SIP phones are able to operate without a computer, whereas VoIP phones need to piggyback off an existing system.

In practice, VoIP represents a wider collection of technologies that continue to add more and more functions to businesses’ phone networks all over the world.

A final thought: Freshcaller’s SIP connectivity feature

For employees who wish to continue to make phone calls over a ‘hard phone’ handset, rather than through their browser, we offer a connectivity feature that’s easy to install, and that leaves everyone happy.

Read our support page to find out just how easy it is to set up.

SIP calling: here to stay?

It certainly seems that way. With old-fashioned PRI lines becoming increasingly redundant, more and more businesses are either adapting their setups or jumping in feet first and making a total switch that will future proof their communications for years to come.

It’s clear that the technology offers the flexibility and adaptability that allows businesses to operate effectively and efficiently against a fast-moving global backdrop.

Illustration by Mahalakshmi Anantharaman

Animation by Vinoth Krishnan


About Freshcaller

Freshcaller is a modern-day cloud phone system that can be used to set up a SaaS call center for customer support and sales. With its cloud-based architecture, Freshcaller brings together the best of legacy features like IVR and advanced call routing capabilities like Smart Escalations, Customizable Performance Reporting to help you set up state-of-the-art call center operations. Freshcaller offers phone numbers in 90+ countries, requires zero phone hardware, and is extremely easy to use.

Visit the Freshcaller website for more information.

 

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