The Great Debate: SIP Trunking vs. VoIP

The Great Debate: SIP Trunking vs. VoIP

If you’re a Telecoms or an IT Provider, you will have likely been faced with a decision at some point on what solution is the best choice for your customer. By working closely with our partners, this is something we get asked all the time.

Should you be offering Session Initiation Protocol (SIP) or a Hosted solution using Voice over Internet Protocol (VoIP)? And what exactly are the differences between SIP and VoIP?

Your business will be aware by now that as the 2025 PSTN and ISDN switch off draws closer, it will bring with it plenty of new opportunities. So our advice is to sell both. Be prepared. Be a provider who can support all of your customers’ needs, and trust us, they will vary with each of your customers.

So what is the difference between VoIP and SIP?

Often, we talk about VoIP and SIP as though they’re two totally different things but technically, they’re not too dissimilar.

When your customers ask about VoIP they are most likely asking for hosted seats, whereas when they ask about SIP, they usually mean SIP Trunking, as a direct replacement for ISDN. Hosted Seats use SIP signalling to initiate the session to send calls to an Internet Protocol (IP) provider. So, essentially, they do the same thing.

It all boils down to the equipment making the call and your customers’ needs and wants. Customers need to move to IP, but what do they want to buy?

With VoIP solutions, as we’ve already mentioned is generally a hosted seat. Hosted seats are usually sold in package deals, bundled with calls usage, which make them easy to buy and sell. These solutions can be extremely flexible and scalable, offering single or multiple user licenses, shiny new IP handsets and mobile or desktop softphone clients. The IP handsets are plugged into a broadband router and/or Power Over Ethernet (POE) switches which provide a single line replacement to the PSTN line over some form or broadband connection.

With SIP Trunking, when it was first launched it provided a ‘like for like’ ISDN replacement. Business customers would have an onsite system, known as a Private Branch Exchange (PBX), which would be serviced by ISDN channels, usually between 2 and 30. By using SIP Trunking, these businesses were able to simply replace their ISDN channels with SIP channels, retaining their existing PBX.

That’s the key difference between the two products: If your customer wants to keep their existing on premise PBX, they need to use SIP. If your customer wants to replace their PBX, they need VoIP.

Which is the best solution for your customer?

The reason to sell SIP is because there are many businesses out there who prefer on premise PBX equipment. Alternatively, you can provide something to bypass the PBX, such as an ISDN to SIP Converter. There are many SIP products on the market, offer features that on premise PBX customers want, and need, even though they’re not ready to move to a fully hosted solution. Features including an online portal, Cloud call recording, reporting and more.

With VoIP there is many that would say it is the future of voice. An onsite PBX has a life span of around 10 years, depending on how desperately your customer intends to sweat their assets. Again, it comes down to your customers’ wants and needs, but who wouldn’t want new future ready IP handsets, an online management portal with call statistics and Cloud call recording, reporting and queuing, all accessed and managed by the customer themselves?

Here’s where VoIP becomes a much more attractive option than your traditional SIP Trunking and PBX. It can offer so much more at the same price, if not slightly more competitive than PBX options. Not to mention how extremely easy hosted seats are to maintain, provide, and support for new telecoms or IT providers looking to sell into this space.

It’s no longer a case of “SIP vs VoIP?” It’s a case of which one best meets the needs of your customer? VoIP is the future, and SIP is the stepping stone for those not ready make the leap just yet. If you’re not selling them both, you should be.

To learn more about our VoIP and SIP solutions contact us today on 01642 697777 or