Towards the end of 2012 installations of
SIP trunks exceeded those of ISDN channels
for the first time. But what you may ask is
a SIP trunk? Simply put, instead of using
a conventional analogue or digital (ISDN)
telephone line to connect to a phone
system for voice communications, IP phone
systems can use a SIP enabled broadband
circuit. The SIP trunk then provides an IP
connection between the IP phone system
and a telephone carrier network (typically BT Openreach).
SIP actually stands for Session Initiation Protocol and is the industry
standard protocol for initiating and terminating telephone calls across an IP
broadband connection. So in essence a SIP trunk is just another application
on an IP network and the end points can theoretically be offered from
anywhere on the internet just like web hosting, mail hosting and numerous
other applications.
The main benefit of SIP trunks is that they are about half the cost of
an equivalent ISDN30 link. Most Internet Telephony Service Providers
(ITSP) offering SIP trunks aimed at business users charge based on a fixed
monthly cost per available SIP trunk channel and then call costs per minute
for calls made. The idea of a ‘SIP trunk channel’ may seem like an abstract
one when considering that SIP is designed for initiating end to end media
sessions over the internet. However it arises from the fact that most traffic
will still ‘break out’ onto the public telephone network (PSTN) and the
network operator will be paying for the cost of an interconnect somewhere
along the line. This charging method also keeps the method of paying for
and ordering SIP trunks similar to what people are used to when buying
ISDN channels – a flat rental fee and call charges on top.
Remember also part of the complete cost of placing SIP calls will be
the IP connectivity to the ITSP which will probably be a separate item and
contract to be charged in addition to the SIP trunks or will be taking up
internet bandwidth paid for elsewhere – so when making comparisons with
ISDN costs or between providers this needs to be taken into account rather
than the headline per channel cost. This is often the ‘hidden cost’ that gets
overlooked.
The other main benefit of SIP trunks is that they allow geographic PSTN
numbers to be routed to any IP address in the world, unlike the traditional
telephone network where numbers are tied to a local telephone exchange.
This gives businesses the ability to advertise what customers will recognise
as ‘local numbers’ and also allows businesses to keep their existing
numbers when moving premises.
SIP trunks are also ideal as a Disaster Recovery (DR) solution. Any number
on the SIP network can be forwarded to any other location – as long as it is
connected via a SIP trunk or a normal telephone line. In the event of a failure
of the main site, calls can be forwarded to home telephone numbers, mobile
or other sites – or a combination of locations/numbers.
Ideally a SIP service will use a secure end-to-end infrastructure without
the public internet being used for service delivery to ensure both reliability
and security of communications. Spitfire has produced a ‘white paper’
explaining SIP trunk technology in more depth.
Visit
to read the white paper in full.
by Tom Fellowes, Sales Director of
Spitfire Network Services
Taking a SIP
The Spitfire Communications Column
magazine
08
agenda
Microwave link brings high-speed
internet to rural schools
One year on from the launch of its first mobile working hub on
the UK motorway network, global workspace provider Regus has
announced the opening of a second ‘Regus Express’ on the M25.
The business centre at Roadchef’s Clacket Lane motorway services
in Kent offers co-working space, ThinkPods (private workstations),
meeting rooms and business support, such as cloud-based printing.
Regus Express can be enjoyed for £5 an hour or £10 a day, or as part
of a Regus Businessworld membership (£35 per month) or a Mobile
Worker trial pack (£10 from Staples).
Rural primary and nursery schools across Stirling, Scotland
have gained much needed access to high-speed internet thanks
to a pioneering project by Stirling Council to replace unreliable
ADSL lines with a carrier-class microwave network.
The network developed by The Networking People (TNP)
provides 24 satellite offices and schools in some of the county’s
most remote locations with a high-speed link to the local authority
network for the first time, whilst also delivering 30% cost-savings
compared to an equivalent fixed-line solution.
The network, which builds on the council’s existing infrastructure,
comprises microwave radio equipment, redundant power supplies
and network switching equipment – all owned by Stirling Council.
Stirling Council’s ICT Infrastructure Manager Alan MacDonald
says: “This has made a considerable difference to the primary and
nursery schools in our rural regions that now have far better access
to learning and teaching resources. They also have much more
responsive access to the county’s cloud-based schools management
system, which in the past had been slow and difficult to access.”
Milton of Buchanan Primary School, for example, went from a
512KB to a 10MB broadband connection giving it access to key
online resources, such as BBC iPlayer, for the first time. The link also
enables it to access cloud-based education resources, IP telephony
and video conferencing.
TNP is working with a number of other local authorities in the
UK, including the Shetland Islands Council, where it is assisting with
the design and development of an extensiveWide Area Network
connecting schools and council offices.
Second M25 business centre
for Regus
ChrisWade, director of TNP,
on-site at Loch Venachar
towards The Trossachs
