ISDN, VoIP, PBX, PSTN… The telecommunications industry is rife with acronyms, technical terms and industry jargon and SIP trunking is no exception. Getting to grips with all these terms can be difficult when you are also trying to run a business, so we’ve put together a useful guide on SIP to help you through. 

What is SIP trunking?

The “SIP” in  SIP Trunking stands for Session Initiation Protocol (SIP) and is an application layer protocol that allows you to run your company numbers over a data connection, as opposed to legacy systems with traditional phone lines. SIP is an alternative to the Integrated Services Digital Network (ISDN), and traditional PSTN (Public Switched Telephone Network) that we traditionally know.

Why do businesses need to be thinking about SIP?

Your business may well be using a PBX and ISDN to make calls already. In which case, you might be wondering why you need to switch. When it launched, ISDN was a great option for businesses, because it can deliver both voice and data services over one line. Nowadays, however, with cheaper, faster, and more efficient options widely available, ISDN is a dying technology and BT has announced that it plans to switch off its ISDN and PSTN phone network and migrate fully to an IP infrastructure by December 2025.

As a result, many businesses have already made the switch to SIP trunking. It’s flexible, quick to provision and provides many advantages for businesses. However, like most IP based technologies, there are some common misconceptions about what SIP trunking delivers. We’ve tackled some of the most common queries below:

Is SIP trunking expensive?

The short answer is ‘no’. If you’re considering switching from ISDN, one of the main benefits you’ll notice from SIP is the significant reduction in telephony costs. You could save up to 50% against ISDN line rentals and 25% or more on call costs depending on your call plan package. 

Does SIP trunking provide good call quality?

There are a few common misconceptions around SIP trunking, including that it offers low call quality and requires a lot of bandwidth. This might have been the case when VoIP first launched, but with advancements in technology and connectivity stability, audio quality can now be crystal clear – providing you have the right data services in place.

Can SIP trunking support business continuity?

Damage to lines, a power outage, or even just moving premises – there are many causes of business downtime. And, when your customers can’t get through, the consequences can be quite significant. Fortunately, SIP trunking offers robust business continuity solutions and can handle emergencies with ease, because calls can be quickly rerouted to an alternative location.

Is SIP trunking flexible enough to support growth?

As an SME, business growth is sure to be high on your agenda. With SIP trunks, you can add new lines and locations without noticeable disruption or the need to invest in additional infrastructure. And should you outgrow your premises altogether, being virtual means that the SIP Trunking can be shifted easily from one location to another, and you can even take your numbers with you.

Can SIP trunking be part of a Unified Communications (UC) strategy?

More and more businesses are making the move towards Unified Communications – in fact, it has been voted the third most important technology set to make a difference to business success. SIP trunking can support a UC strategy, as it is already the preferred protocol to process voice, video, instant messaging, and multimedia calls, such as white board sessions. 

Making the move to SIP trunking

SIP trunking isn’t the only option out there, of course – if you don’t have a PBX, you could consider Cloud-Hosted Telephony as a way of future-proofing your business communication. And, if your organisation is still relying on ISDN, there’s still time before it becomes fully obsolete. But, given the flexibility, performance, and cost efficiency of this technology, we would encourage our customers to consider switching sooner, rather than later!

Ready to make the switch to SIP trunking? Call us today on 01908 324 270 or email our team at to find out more.  

Add comment Share: Twitter   Facebook   Linkedin   Google+