What is SIP?

SIP meaning: the protocol behind modern business communication

SIP is one of those terms you’ll run into when looking into business telephony or SIP Voice over IP. But what is SIP exactly? It's not the same as VoIP, even though people often mention them together. VoIP stands for Voice over IP calling over the internet. SIP is the protocol that makes it all possible. Think of it this way: VoIP is the service, SIP is the set of rules that makes that service work.

There are other protocols that enable VoIP with SIP, but SIP is by far the most common. Why? Because it’s flexible, easy to integrate with other systems, and supports different types of communication like voice, video, and chat.

Using Xelion? Then you’re already working with a stable VoIP SIP trunk provider setup, without lifting a finger. Easy does it.

What is SIP?

SIP stands for Session Initiation Protocol. It’s a communication protocol used to set up calls via the internet. Think of voice calls, video meetings, or messaging: SIP connects the devices. You use it unknowingly when calling through a VoIP SIP provider like Xelion. This seamless integration of VoIP and SIP helps your business communicate better, from anywhere.

SIP: the smart foundation of business telephony

Businesses are switching to VoIP SIP trunk services en masse, and SIP is the backbone of that system. Instead of traditional phone lines, you use an internet connection. That means lower costs and more flexibility. And with SIP trunking vs VoIP, you can easily link multiple devices, locations, and users to one central phone system.

That’s especially useful if your team works from different places, or if you want to be just as reachable at home or on the road as you are at the office.

How does the SIP protocol work?

The SIP protocol works like a digital conversation request. When you dial a number, your phone (or softphone) sends a SIP request to the recipient. Once they accept, the session begins. SIP doesn’t handle the media (sound or video)—that’s up to other protocols like RTP but it sets up and manages the session.

The key part here is the VoIP SIP trunk. This is also known as trunk VoIP or SIP trunking. It connects your internal phone system (like Xelion's cloud platform) to external phone networks. Think of it as a modern, flexible alternative to ISDN.

What is a SIP circuit?

A SIP circuit is a logical internet connection that allows multiple simultaneous calls. The more circuits you have, the more calls you can make at once. Xelion makes this scalable: easily adapt it to your organization’s size.

How secure is SIP?

SIP is safe—as long as you set it up correctly. Just like any online service, the basics are solid, but you need to take steps to prevent abuse. Use strong passwords, keep your software up to date, and limit access to your SIP Voice over IP environment.

With Xelion, we’ve got you covered. Our platforms run in highly secured data centers and we use encryption (TLS/SRTP) for both signaling and voice data. That way, no one can listen in or hijack your phone traffic.

Want to combine SIP with your firewall or an SBC (Session Border Controller)? No problem. Xelion supports these integrations. You can even integrate SIP Voice over IP with your firewall or Session Border Controller. Want full control? Xelion supports trunk VoIP integrations tailored to your setup.

Why is SIP useful for your business?

SIP gives you full control over your accessibility. Link landline numbers to mobile phones, integrate your phone system with your CRM, and switch between work locations instantly. And with VoIP and SIP, you only pay per user—not per line.

•  No expensive hardware investments
•  Scalable and flexible
•  Ideal for hybrid work
•  Reachable anytime, anywhere

In short: SIP fits modern companies that need flexibility, reachability, and scalability through VoIP and SIP.

Ready to switch to SIP Voice over IP?

Already using VoIP or thinking about moving away from traditional telephony? Then chances are you’re already working or will soon work with SIP Voice over IP. At Xelion, we use SIP in a way that fits your business. Curious how that looks? Or how your current VoIP trunk provider setup connects with Xelion? Ask us we’ll think it through with you.

Summary

SIP (Session Initiation Protocol) powers internet calling. It starts, manages, and ends calls smoothly. With SIP Voice over IP, your business becomes scalable and ready for the future. Add VoIP and SIP to your setup, and experience full flexibility.