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What Is a SIP Phone? Your Complete Handbook

This article was updated on July 1, 2024

Even with messaging apps, email, and other communication methods, the vast majority of businesses still find themselves using the phone every day. However, phone systems don’t have to be old-fashioned. While public switched telephone networks (PSTNs) might cover your basic business calls, they don’t allow for video calls or other advanced features. Instead, take a look at a modern alternative: SIP phones and VoIP technology.

Photo of a smiling agent sitting at her computer talking to a customer through her headset. A series of small vertical lines representing sound run across the frame.

What Is a SIP Phone?

What does SIP phone mean, exactly? SIP stands for Session Initiation Protocol and is a universal language for device communication. Basically, a SIP phone handles inbound and outbound calls by using the internet rather than copper wiring. That means they fall under the Voice-over Internet Protocol (VoIP) umbrella.

In simple terms, SIP phones can connect to nearly any type of device or communication channel. This is why you can use a SIP desk phone for audio and video.

How Does a SIP Phone System Work?

The SIP telephony process breaks down into some basic steps:

1. First, you pick your SIP phone and dial a number just like a traditional analog phone.

2. At this point, your device sends an invite request to start a call.

3. The recipient device exchanges information with your phone until reaching a handshake-like agreement. The two devices now have a common language for communicating.

4. A session is initiated. This could be for a video or voice call.

5. When you speak, your SIP device converts audio into digital data packets. It then sends this information across the web, near-instantaneously.

6. On reaching its destination, the data packets are converted into audible speech and heard by the receiving party.

7. When finishing a call, you hang up as usual. The SIP technology sends a Bye request, terminating the session on both ends.

The nuts and bolts of this process can be quite complicated. For users, the voice or video call happens seamlessly. It’s just like using your traditional landline phone, only much better since you can add extra capabilities.

The Different Types of SIP Phones

SIP phones use different technology than traditional landline phones — but what exactly this is can vary. Generally speaking, most SIP phones are either purpose-built desk phones or softphones that use mobile apps.

Desk or Hardware SIP Phones

Physical SIP phones come in many forms. Basic sets may look like a normal telephone, with the only difference being that they connect digitally rather than in the traditional, analog way. Many phones include screens as well.

Desk SIP phones provide HD audio and often come with advanced capabilities. These devices feature customizable buttons so that users can access the functionality they need quickly.

Businesses can also opt for wireless SIP phones for maximum mobility.

LCD SIP Phones

Many mid-range handsets come with LCDs that provide an intuitive interface. A phone like the Poly CCX 600 comes with a touchscreen — no buttons required! This provides a familiar user experience in a time when we seem glued to our smartphones.

Video SIP Phones

Some phones come with a built-in webcam on top of an LCD display. This allows for video calls, making them a great way for managers to maintain face-to-face interactions with remote employees or for sales professionals to make speaking to prospects more personal.

Conference SIP Phones

Phones built for conferencing use full-duplex technology to pick up sound from 360 degrees. The Polycom Trio 8500 has a microphone with a 14-foot pickup and is ideal for meeting rooms.

That way, rather than everyone having to dial in individually, you can make calls from one meeting to another, without compromising on sound quality.

SIP Softphones

Softphones offer an alternative to modern SIP phone users. Even if you don’t provide devices, every member of your team has their own smartphone. What if they could, for example, use their iPhone or Android phone for SIP calling? A report from Statista predicts 93.5 million U.S. employees will be equipped with some level of mobile device for work by 2024. 

To use a softphone, you will need to sign up with a SIP provider like Vonage. With a VoIP mobile app, you can tap into the power of IP calling — as long as the device has a network connection, you can make and receive calls from anywhere in the world.

Softphones give your team ultimate flexibility and let them use their preferred devices. They also make it easy to promote a bring-your-own-device (BYOD) policy, reducing the upfront costs of using a SIP phone system.

The Benefits of SIP Phones

So now you understand what a SIP phone is, you might be wondering what makes them worthwhile — especially if you already have a working phone system. Well, here are just some of the benefits:

Higher Scalability

Adding a SIP line to your network is easy. Users with administrative privileges can set up and configure a new number in minutes. It is much quicker than installing new lines for a PSTN system and doesn’t require additional space (or, if you’re using softphones, more hardware).

You can add a new line when needed. With providers like Vonage, you can also add or upgrade capabilities to scale your business operations.

Greater Mobility

A Statista report found that one of the top three reasons employees seek a new job is for flexible working. By embracing SIP phone technology, you can appeal to a wider talent pool via better supporting remote and hybrid team members. Every member of your team can enjoy greater mobility using SIP to break the chains of their desks.

Your team can use their mobile devices for VoIP communications, or you can provide specialized hardware. Plus, with features like out-of-hours call routing and forwarding, it’s easy to remain reachable no matter where you are.

Increased Flexibility

Mobility isn’t the only thing that makes SIP solutions flexible. Most platforms are highly customizable, from user permissions to the caller experience. You can route incoming calls based on business hours, use skills-based routing, or set custom call groups. Tools like virtual receptionists and call parking also make your agents’ (and customers’) lives easier.

Customize reporting and analytics to track the call metrics you value, such as call quality or average handling time. Most systems are straightforward to use, giving you the control of how to use them.

Reduced Costs

A SIP system can significantly reduce the amount of money you spend on business communications. First off, you don’t need to invest upfront in new phone lines and other traditional equipment.

Secondly, while you can invest in physical SIP phones, you can also use mobile devices with a softphone app. This reduces set-up costs dramatically.

These aren’t the only savings, however. VoIP calls with a service like Vonage offer low rates for international calls and rely on set monthly subscription fees. That way, you only pay for the features and lines you use.

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Gain Powerful Capabilities

The capabilities of SIP phones blow regular, analog telephones out of the water. Even basic packages often come with a dizzying array of options. 

Some common features to expect include:

How To Set Up a SIP Phone

Setting up a SIP phone doesn’t need to be complicated. The following steps will show you how to connect SIP phones to your network.

1. Pick a SIP Provider and Device

This is probably the hardest part of the set-up! You need to do your due diligence and research the available options. Make sure to prioritize which features are most crucial to your business and find a platform that fits your budget.

You will also need to include your implementation plan as part of the decision-making process. Are you planning to install a fleet of SIP desk phones or will you opt for BYOD softphones? Knowing this will help you choose the best solution for your organization.

2. Gather User Information

Next up, it’s time to start adding users to your SIP telephone network. You’ll need to confirm the user credentials supplied by the service provider.

Basic user information you’ll need includes:

  • name, title, and associated privileges

  • SIP email address

  • SIP password

  • outbound proxy

3. Connect the SIP Phone to the Network

For physical phones, simply power up the device and connect to the network. You will do this either wirelessly or by plugging into the local area network (LAN) with an ethernet cable.

Alternatively, if you’re using a smartphone, download the mobile app and open it once it’s installed.

4. Login to the SIP Network

For desk phones, you may need to access the device's IP address to access the configuration settings. Type the IP address into the web browser of a desktop computer. From here, you can access any settings required to get the phone ready to use.

For other SIP phones, you just need the user credentials to log into the IP portal. This will work in the same way with virtual softphones.

5. Configure the Phone

Once you’ve gotten into the phone settings, you can set everything up for the user. Admins add web addresses for the SIP server and customize any proxy settings. Each SIP service will have a range of advanced configurations, such as Quality of Service (QoS) and codecs for audio and video.

You can probably ignore most of this for now, as it’s usually in the hands of a specific admin or IT team, rather than every single user.

6. Register and Test

Once you’re happy with the basic and advanced SIP settings, click the “save” or “register” button. Now, your SIP phone is ready to go. It’s best to test and confirm your new business SIP phone is working as intended.

Dial a few numbers and test out other features like messaging. If something’s not working, it’s best to get in touch with the support team of your hosted phone system.

SIP vs. VoIP: Understanding the Difference

SIP and VoIP are often used interchangeably. While they are related terms, conflating the two is a common mistake that spreads confusion.

VoIP is a broad term covering any technology that allows the sharing of voice data over the internet. Audible speech is converted into digital packets, sent across the web, and reconverted to voice on the receiving end. VoIP calling solutions often also provide video, messaging, and other capabilities.

Other types of VoIP technology include:

  • H.323

  • H.248

  • Real-time Transport Protocol (RTP)

  • Session Description Protocol (SDP)

  • Jingle

  • Skype protocol

  • WebRTC

Session Initiation Protocol is a type of VoIP. We define SIP phones according to the user of this protocol. It’s a standardized language that allows seamless communication between devices.

SIP uses the internet to connect for video, text, and voice messaging. Sessions start, run, and stop as needed providing a stable, secure connection.

What Is the Difference Between SIP Phones and SIP Trunking?

SIP phones and SIP trunking are related but separate aspects of VoIP calling. SIP phones use Session Initiation Protocol to connect and communicate with other devices.

SIP trunking, on the other hand, is a service provided by internet business phone providers that allow the connection of a IP-PBX (internet protocol private branch exchange) system to the public telephone network.

With SIP trunking, you can use your legacy phone system to gain many of the benefits of VoIP telephony. The primary purpose is to use virtual numbers to make and receive calls. SIP trunking is also compatible with other types of digital communication, including video conferencing and chat.

Evolve Beyond SIP Phones With a Powerful Business Communications Suite

If all you need is the ability to make phone calls over the web, any basic SIP phone system will do. However, many organizations will want more than that.

Vonage offers a range of unified business communications solutions for business. Our platform empowers your team to communicate with voice, text, and video from anywhere and on any device. Not only does our Business Communications solution include features like unlimited domestic calling, a virtual receptionist, and the ability to host video conferences with up to 200 participants, but we also offer a range of SIP desk and conference phones as well as SIP trunking to tap into your existing setup.

Don’t waste time with a sub-par PBX. Schedule a conversation with our team today to find out what we can do for your business.

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