The IP telephony world can seem like a sea of acronyms sometimes. SIP and VoIP are just two of the acronyms flying about, but do they mean the same thing? Are they similar at all?
Is SIP the same as VoIP? SIP is not the same as VoIP. SIP is often used with VoIP, but it isn’t the same thing. SIP is a protocol that enables calls over a data connection.
So while SIP and VoIP aren’t the same thing, they often work together. To demonstrate how SIP and VoIP work together, I’ll explain what both are and they work.
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What Is SIP?
SIP stands for session initiation protocol. It is a popular internet telephony protocol that is often used with VoIP.
An internet protocol is a set of rules that dictate how internet-enabled devices communicate with each other. In the circumstance of VoIP, SIP will define how the two endpoints communicate, whether those are IP phones or other internet-enabled devices.
The session initiation protocol is used in all types of internet communication sessions. In the context of VoIP, SIP establishes and manages the session and terminates the connection once the session is concluded.
In the context of a phone call, this means the session initiation protocol initiates the phone call, sends signals between the two devices, and ends the phone call when either endpoint signals that the call is complete.
SIP isn’t the only protocol used with VoIP, there are actually several. However, SIP is the most widely used. If you’re already using a cloud-based telephone system, chances are it uses SIP.
What Is VoIP?
VoIP, pronounced ‘voyp’, stands for Voice over Internet Protocol and is often referred to as IP telephony. VoIP is an umbrella term for a group of technologies that allow you to make and receive voice communications and multimedia sessions over IP networks, for example, the internet.
Traditionally, calls were delivered using the public switched telephone network, better known as the acronym PSTN. With IP telephony, calls are instead made over a data connection.
So how does VoIP work? When a phone call commences (thanks to SIP, or other protocols like H.323), the audio signals are digitised and transmitted as IP packets. The signals are encoded using codecs such as the G.711 and G.729. When the signals reach the endpoint(s), they are decoded and the call seems like an uninterrupted stream of audio.
While VoIP hasn’t always been as reliable as it is now, IP telephony has been revolutionary for a lot of businesses. Although VoIP covers a wide umbrella of technologies, there are usually several benefits to having an IP-based telephone service for your business. For example:
- Cost-effective licences: Although this depends on your provider and your current setup, moving over to IP telephony can usually save your business a lot of money. A licence is the equivalent of a line; each person making calls needs one. VoIP licences are usually much cheaper than traditional lines so businesses can save a lot of money.
- Future-proof: Across the world, countries are shutting down their traditional telephone networks. For example, in the UK, BT plans to shut off the ISDN and PSTN networks by 2025. The largest telecommunications providers across the world are investing heavily in IP telephony instead, so you’ll be using a future-proof technology if you embrace VoIP now.
- Flexible: IP-based telephone systems tend to over much greater flexibility than traditional telephone systems. For example, you can quickly divert calls to any number. Or you can download an application on your phone to use all the features of your system no matter where you are. The flexibility afforded by this technology is ideal for any company.
How Do VoIP And SIP Work Together?
SIP is one of the technologies that often falls under the VoIP banner. Although VoIP can use other protocols, SIP is frequently used. VoIP is usually deployed with SIP, so it’s fair to say that they work together very well.
In this section of the blog post, we are going to take a look at how VoIP and SIP work together.
How SIP Is Used
The session initiation protocol (SIP) can be used to start, maintain, and terminate multimedia communications. When used in a VoIP deployment, SIP is used to start and manage voice communications using an IP network.
A voice over internet protocol phone call is usually split into two stages. When the end user picks up the phone and commences a call, this is the ‘call setup’ stage. During this stage, SIP is used to initiate the call and connect the two or more parties involved. Once the call has been established, voice data can transfer between the endpoints involved.
Once the end users reach the end of the call, SIP transmits termination signals to the endpoints involved to end the communication.
So while VoIP technologies allow for communication using a data connection, SIP is used to actually enable the connection between end users.
As I mentioned before, SIP is widely used although there are other protocols that can be used. So why is SIP used so much when there are other options out there? Here’s a look at why so many providers and businesses use SIP rather than anything else.
Why Do Businesses Use SIP Over Other Protocols?
There are several protocols that can be used with VoIP, so why is SIP so widely used? As part of writing this blog post, I spoke to 4 providers in the UK about why SIP is more popular than the other protocols that are available.
The Best For Unified Solutions
Despite SIP being widely used for VoIP, the protocol wasn’t actually developed for the telecommunications industry. In fact, SIP has its roots in the internet community rather than the telecoms industry. Because of its roots, SIP is capable of integrating with a wide range of other internet-based applications, systems, hardware and software as well as VoIP systems.
If your business uses a lot of internet-based applications, systems, hardware, or software that are already using SIP, it makes more sense to use SIP for VoIP too when you consider unifying your solutions. It seems that businesses are gradually moving towards unifying their solutions, and the providers I spoke to when creating this blog post all agreed that SIP was the best option for VoIP as a result.
Your Existing IT Team Can Manage SIP
If you have an existing IT team, it is probable that they can get to grips with SIP and manage it. This negates the need to hire additional team members that specialise in voice over IP.
SIP is a basic text-based protocol. According to the providers I spoke to, it is very similar to the widely used HTTP. Because IT professionals likely work with HTTP on a daily basis, they can quickly figure out what SIP is and how it works.
With VoIP using SIP, voice calls are now data. In previous times, you’d have to hire telecommunications specialists to look after your telephone system because it was so drastically different from what your IT team would deal with. Now, an IT team can manage VoIP and SIP since they are both designed with unified communications in mind and because VoIP calls are essentially just another form of data.
VoIP Hardware Designed With SIP Compatibility In Mind
SIP is the most widely used protocol when implementing VoIP. As a result, businesses manufacturing VoIP hardware know the importance of making sure their equipment is SIP-compatible.
Many hardware manufacturers design their VoIP equipment to ensure it has SIP compatibility. Most don’t do the same with other protocols, which means you can have a harder time finding compatible equipment.
Conclusion: SIP And VoIP Are Different, But Often Used Together
SIP and VoIP are different, but also closely related. In most VoIP deployments, SIP will be the protocol used to initiate, manage, and terminate calls.
There are many benefits to using the SIP protocol, as I discussed with several big players in the telecommunications industry. It’s easy to see why both are often used in tandem.