How do SIP phones work? All you need to know on SIP and the Benefits of SIP Phones

Research shows that a growing number of small businesses are looking to cloud phone solutions to lower costs, increase efficiency and boost productivity. SIP trunking is one such solution. SIP, short for Session Initiation Protocol, has been a key topic of discussion in companies and IT departments looking to expand and enhance their company’s phone service while still lowering costs. So, what do you need to know about SIP phones before you can consider them as suitable solutions for your enterprise? This article details the key aspects about SIP including; what is SIP? How do SIP phones work? How can a SIP phone system benefit your company?

What is SIP?

SIP or Session Initiation Protocol is a communication protocol used to manage multimedia communication such as voice and video calls. To make use of SIP, you need SIP phones that establish communication over the internet. Unlike legacy phone systems that relied on physical lines and cables, SIP phones use the internet to make and receive calls. This also means that they are significantly more secure and reliable than traditional phones.

As organisations continue to embrace digital transformation, Session Initiation Protocol allows organisations to adopt unified communications as it brings together most of today’s business communication including basic phone capabilities, email, video, instant messaging and more. For enterprises that are looking for reliability, scalability and improved functionality, SIP phones allow them to move from basic voice communications and expand into video and instant messaging.

Features of SIP Phones

Visually, a SIP phone looks like the typical office phone. However, beneath the surface, SIP phones offer far greater functionality than common office phones. In addition to placing and receiving phone calls, SIP phones can manage calls including transferring callers to different extensions and placing callers on hold. It is also important to note that SIP phones deliver higher call quality than traditional phones.

The technical differences that draw IT leaders and experts to this technology include the fact that SIP phones connect to a VoIP phone service without the need for servers or extra hardware. This also means that they are significantly easier to install and consequently easier and cheaper to maintain.

In essence, by choosing SIP phones, you are getting a reliable phone service loaded with business VoIP features without the typical hassles.

Key Features of a SIP Phone

  • Basic and advanced call forwarding
  • Conference calling
  • Auto-attendant
  • HD phone calls
  • Hold with optimal music
  • Call recording
  • Custom caller ID
  • Shared caller appearance
  • Desktop and mobile app integration

How SIP Phones Work

At the most basic level, SIP phones operate pretty much how you use the internet on any other device. If you listened to the network traffic, you would be hard-pressed to find a difference from HTTP traffic when accessing web pages.

When making a call from a SIP phone, the device notifies the SIP server it is connected to – typically your business VoIP service. The SIP server then initiates contact with another extension or patches the call over to the Public Switched Telephone Network (PSTN). When the receiving phone answers, the call is established. During the call, SIP phones automatically negotiate the status and quality of the call in real-time.

This is a big contrast from a traditional phone system that consists of two parts – the PBX responsible for call management and PRI lines which connect calls to the PSTN responsible for routing calls. With SIP, a virtually installed SIP trunk uses the internet to connect to the PSTN and thereby eliminates the need for PRI lines.

The thing that stands out the most about SIP-based telephony is the minimal equipment, hardware and infrastructure requirement.

Benefits of SIP Phones

There are numerous reasons why SIP phones are the way of the future including;


In addition to the basic call function, SIP phones can also perform the following functions without the need for extra devices.

Determine user availability

  • Identify user location
  • Negotiate media capabilities
  • Multimedia conferences
  • Instant messages
  • Enhanced 911 emergency calls

Cost Savings

Switching to SIP telephony has been shown to result in cost savings of up to 70% particularly with the help of a reputable IT solutions firm. This is largely due to the elimination of installation, hardware purchases and maintenance costs.


Supporting a growing business can prove exceedingly expensive particularly with the traditional phone system. With SIP phones, you only buy and pay for what you need without having to make guesses about future needs or deal with underutilised resources.

User Friendly

Installing SIP phones is quite easy and straightforward while maintenance is done through a simple online control panel. Additionally, the system consolidates all your business communication making it easier and efficient to improve business communications. This also means that you only need to train employees on one device. The additional features also go a long way in improving user experience and enhancing business productivity.

Does Your Business Need SIP Phones?

SIP phones are here to stay and are the way to the future. If you are wondering if you need SIP phones, you probably do or will in a few months. At AdEPT, we help organisations of all sizes find the right voice solutions for their needs and move towards unified communications. Our unified communications are based around key partnerships with leading providers including Ericsson-LG’s iPECS and Avaya for AdEPT Nebula Voice. With close to 20 years of experience, we have the skills and expertise to facilitate a smooth transition and help you reap the full benefits of SIP phones. Contact us today to learn more about our voice services.

Sami Malik

Written by Sami Malik

Marketing Campaigns Manager