SIP Trunks

Telephony is moving from PSTN to much more modern and flexible SIP trunks.

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.

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. By 2017 major telcos such as BT, KPN, France Télécom, Deutsche Telekom and Telecom Italia will no longer offer ISDN lines.

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 Telephone system. Phone numbers and DDI’s are linked to the SIP trunk. In most 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 & DDI Rental – The monthly fee to have a number of lines installed at your office drops significantly with SIP trunks. And DDI’s cost a lot less.
  • Lower call charges – Competition has driven down call charges significantly. Some SIP trunks come with bundled minutes.
  • 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.
  • 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.