Products & Solutions

SIP trunking PSTN replacement

BT One Voice SIP trunk UK

The benefits

Future-proof your communications

Combine voice and data with a flexible service that makes the most of your investment and takes you a step closer to unified communications (UC).

Use the latest technology to work more effectively
Combine your voice and data communications and make the most of your WAN investment with SIP trunking at the heart of your UC plans.

With UC, your staff will communicate faster and more efficiently, whether they’re in the office or on the move. And UC services like VoIP, instant messaging, presence, conferencing and video will suit customers too. People increasingly expect them, and you can add services as you need them.

Pay as you go
Don’t pay all year for the number of channels you need to cope with busy periods. We’ll work out your base requirements for quieter times and you can plan effectively for seasonal peaks and troughs by scaling up or down. There’s only a nominal reservation charge when channels aren’t being used

Better cost management and more resilience
Built-in resilience means more business continuity for free – you can automatically route to another location if the usual one isn’t available. One Voice SIP trunk UK can be more cost-effective than ISDN30 and you’ll save on charges and admin by bringing your calls and data together over a single IP network.

What it costs

What it costs

Channel prices start from £5 per channel per month (ex VAT). Volume and term discounts are available too, so this can be reduced further It may also be necessary to upgrade your data network. For more information on pricing, click “Get a quote”.

More reasons to buy

Tried and trusted

One Voice SIP trunk UK is part of BT One, our range of technologies that bring voice and data together. So you know you’ll be extending your communications network with a proven series of products and services.

We can manage the service for you in full, and it’s all available with our award winning Managed Security Services.

Technical specs

Simple, cost-effective unified communications

SIP trunks are fast becoming the way to connect an IP Enterprise switch (PBX) to the PSTN, using a data network rather than ISDN30.
By connecting an IP PBX with BT’s next generation network, One Voice SIP trunk:

  • routes all company voice traffic onto your BT data network
  • offers one gateway breakout to the PSTN – removing the need for local (PBX) PSTN connectivity – so no PRI gateways, and no ISDN30
  • needs just one IP access line for both internal and external data and voice traffic

One Voice SIP trunk UK not only gives you core features and functionality similar to traditional voice services, but also a range of new features:

  • trunk aggregation and centralised PSTN access potentially cut the number of channels you need
  • IP resilience from targeting an incoming trunk to two different IP addresses
  • choice of codecs so you can decide how you use your bandwidth
  • flexibility to raise or lower the number of channels you rent and respond to seasonal or business peaks and troughs

Channel types
Choose from four trunk categories:
Light – best for occasional use
Normal – best for normal business desk phone users
Intense – heavy-duty trunks engineered for constant use, day-in, day-out
Dynamic – covers short or medium term, increased capacity to adapt to seasonal call peaks


Available in the UK

There is a SIP option on our One Voice global portfolio – known as One Voice SIP trunking.


Works perfectly with our other UCC services

We’re an accredited partner of Avaya, Cisco and Microsoft so we can supply, install and manage your UCC and voice services in full.

Service Level Agreement

Peace of mind

We set ourselves high standards for performance and service and can arrange dedicated Service Level Agreements on request.