Acuity Unified Communications Limited
Making the move from PSTN to SIP trunk: SIP trunking explained

The trusted old Public Switched Telephone Network (PSTN), with its Analog, ISDN BRI, E1 or T1 lines, is to disappear. Telephony is moving from PSTN to much more modern and flexible SIP trunks.

The big telecom providers are fast phasing out the old PSTN functionality, and are moving customers to IP. And so a SIP trunk and a phone system upgrade in the near future is going to be inevitable.

In the UK, ISDN lines are down to less than 3 million lines, from 4.7 million lines in 2007 and the trend is accelerating.

As a result, Session Initiation Protocol (SIP) trunking has increased by 62 percent in 2015 from the prior year, driven primarily by North America. This guide explains what SIP trunks are, their advantages and how you can make the move.

What are SIP trunks?

SIP trunks are telephone line trunks delivered over IP using the SIP protocol. Using this standard protocol, telecom service (VoIP) providers connect one or more channels to the customer’s PBX. Phone numbers and DIDs are linked to the SIP trunk. In many cases numbers can be ported to the SIP trunk.

Benefits of SIP trunking

But our farewell to the PSTN brings many benefits. SIP trunks deliver:

  • Lower monthly Line & DID Rental – The monthly fee to have a number of lines installed at your office drops significantly with SIP trunks. And DIDs cost a lot less.
  • Lower call charges – There are many SIP trunk providers and competition has driven down call charges significantly. Some SIP trunks even come with unlimited calling.
  • Better customer service – Provide better customer service by adding more geographical and international numbers. Quickly and easily add numbers to your SIP trunk and terminate them on your IP PBX – you can give customers more options to dial in at a significantly lower cost. Customers can contact you more easily and sales will increase.
  • Move offices and keep the same number – SIP trunks are not bound to a location, so it’s easy to move offices without having to change your stationary or inform your customers. There is no longer any need to pay to forward phone calls to the new offices.
  • Eliminate VoIP Gateways – SIP trunks will eliminate the need to buy and manage VoIP Gateways. All phone calls come in via IP. No extra conversion often means better quality too.
  • Leverage a modern IP PBX – Modern IP PBX / Unified Communications solutions will give customers increased productivity, mobility and boost sales. Connecting an IP PBX to SIP trunks is much easier than via the PSTN.
  • Flexibility – It is easy to add channels to your SIP trunk to cope with increased calls. A simple phone call will allow you to add channels, and often this can be done immediately. Compare that to the delay in having additional lines installed and then having to upgrade your old PBX to handle more lines!
  • Correct number of channels – With SIP trunks, you can easily choose the correct number of channels that you need. Using ISDN/T1, you often have to choose to add either 15 or 30 lines. This usually means you end up with expensive extra capacity.

SIP Trunk Plus, powered by Acuity, is an all-in-one telephony solution that offers SIP call recording for both your mobile and office numbers, an innovative Toll Fraud Mitigation solution and economical SIP Trunking that is compatible with all leading phone systems, as well as being fully tested and approved by 3CX.

Not only are you not required to upgrade your telephony hardware, but SIP Trunk Plus also provides you with more control over your own numbers. Manage SIP call recording per extension number and enable and disable at will; create and manage SIP trunks and clients without waiting for us to do it and purchase new numbers as you need them from your very own web portal.