How to Integrate WebRTC with SIP: VoIP Phone System

Maulik Shah
5 min readOct 31, 2022

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What is Session Initiation Protocol (SIP)?

Among the most fundamental communication technologies of the past decade is the Session Initiation Protocol (SIP). SIP introduced brand-new, uniform control techniques. It is a text-based signaling protocol to handle media sessions between two IP-connected endpoints. Due to its widespread use in Voice-over-IP (VoIP) communications, SIP’s capabilities have grown exponentially.

Internet telephony and the transmission of multimedia data between two or more endpoints are the main applications of SIP. For example, a user can start a phone call using SIP with another user or a conference call with several participants.

SIP is neither audio, video, or data; the protocol is not tied to any one form of media. SIP initiates and terminates IP communication sessions, such as collaborative video conferences or voice calls between two users. Sending messages — in the form of data packets — between two or more defined IP endpoints, commonly referred to as SIP addresses, starts a session. Every SIP address is associated with either a hardware SIP client — such as an IP desk phone — or a software client — a softphone.

What is WebRTC, and why is it important?

A VoIP technology that builds on and incorporates SIP features is WebRTC. However, the two infrastructures embrace a symbiotic relationship in which each supports the other. WebRTC makes communication easier by eliminating barriers. This innovative solution works with browsers on both desktop and mobile devices and makes use of plugin-free APIs.

WebRTC is a communications technology that enables users to add real-time media to every web browser, including audio, video, and file transfers. This implies that a softphone does not need to be installed on a user’s PCs, smartphones, tablets, or other devices. Instead, real-time communication capabilities will be available on any device with a web browser. As a result, developers can create cross-platform communication applications without having to work with a slew of technologies or codecs.

Users who want to add real-time audio and video to an existing service can make the most out of WebRTC.

WebRTC makes use of the three key Javascript APIs:

  • Media Stream: It gathers audio and video by using the camera and microphone on your device.
  • Peer connection: It transmits both audio and video. Enables audio and video peer-to-peer communication. This entails establishing the connection, monitoring it, and cutting it off.
  • Data channel: It transmits all kinds of data. Enables the bidirectional flow of data between two peers.

These APIs enable browsers to use and transmit data, audio, and video to other browsers or endpoints.

How does calling from SIP to WebRTC function?

Establishing phone calls over the internet has become possible thanks to WebRTC, a relatively new technology. This implies using intermediaries like web browsers or apps to handle the communication rather than directly connecting your devices. This form of call has the advantage of being made using any device, regardless of the technological capabilities of that device.

Making a WebRTC call doesn’t require a high-end smartphone or tablet; in fact, many people prefer doing this on budget smartphones and tablets since they are more accessible.

  • The web browser or app of the other party is connected to your device when you place a WebRTC call. Therefore, the other person doesn’t require any complex software to participate in the conversation.
  • The WebRTC technology must first be enabled on your device before you can make a phone call using it. To do this, go to your settings and choose “Phone” from the list of available options.
  • Once established, you will have access to several features that let you place calls using WebRTC technology. The fact that WebRTC is secure is one of the major benefits of using it to make phone calls.
  • This is due to the fact that your calls are routed via a server rather than directly between devices. This indicates that your conversation is private and that unauthorized parties cannot access the information you are disclosing.

You should keep the following in mind when placing a WebRTC call:

  • Always exercise caution when connecting to untrusted websites or networks. If you’re not careful, someone else who is connected to this address — you don’t know who — might be able to intercept your message.
  • Make sure that your devices are connected to the same network as the other party. This will guarantee that the call can be conducted smoothly.
  • Always use a VPN to ensure your security and privacy when utilizing WebRTC for phone conversations. A VPN encrypts all of your traffic to ensure that no one else could intercept or tamper with your communication.

Method of connection for WebRTC & SIP

  • WebRTC merely sets up the media and explains its capabilities. Due to this, a method of exchange is still required to start a session. WebRTC is ideal for users who want to add real-time audio and video to an already existing service. But in order to go beyond this function and interact with others, a protocol will still be required. A communication and session-setting protocol, akin to SIP, will be required by WebRTC.
  • SIP-compatible devices can communicate with one another directly. SIP servers and SIP endpoints are frequently connected through the use of supplementary middleware (SIP proxy) and different protocols.

SIP capabilities enhanced by WebRTC

Why use WebRTC with SIP? What value does it add that it is supplanting conventional forms of communication in most corporate sectors? Although WebRTC and SIP are independent technologies and can work together, doing so can vastly enhance an organization’s communication channels. The ability to receive incoming calls via the Internet without using the PSTN and a more seamless user experience with one-click audio contextual communication are two of the biggest advantages of integrating SIP into WebRTC. By utilizing a single, well-defined protocol, internet users can connect to legacy PBX hardware in this manner.

The HD audio quality is another perk of using SIP and WebRTC instead of PSTN. Using WebRTC codecs, which are better suited for use over the open internet, results in enhanced audio transmission reliability as well. Almost all contemporary softphones and PBXs, including FreeSWITCH, Asterisk, and others, have this codec fully integrated.

As WebRTC usage increases, VoIP and SIP will become more robust, usable, and versatile as a result. Businesses that use more extensive WebRTC adaptations can give their customers superior web browsing experiences as well as better communication capabilities. Innovative technologies that enable straightforward, direct, and personalized interactions will become increasingly important for getting an edge over the competition as the value of individualized communications and platforms increases among modern consumers.

Benefits of SIP to WebRTC calling

When one considers the benefits that SIP and WebRTC bring to users and developers alike, it is simple to understand the frenzy around them. The benefits of SIP to WebRTC calling for business communications include:

  • High quality: The quality of media shared using WebRTC VoIP is optimized by low latency.
  • Flexibility: Employees do not need to carry extra equipment because this technology is accessible via browsers. It allows you increased mobility and flexibility.
  • Cost-effective: WebRTC calls are less expensive than traditional landlines as they are made over the internet.
  • Continue reading…

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Maulik Shah

I like to read and write about VoIP, Softphones, Business Productivity, Work From Home Empowerment and much more.