0330 122 3000

At Simwood, we're proud to empower your developers with as much control and technical mastery as possible.


API and Portal

Our market-leading API is at the core of everything we offer. All aspects of our services can be controlled via the API, making it easy to integrate our service with your own.

Our own portal is built entirely on our API, bringing unique and powerful features to a wider audience, in a more human-friendly format. We believe in customers having full control over their service in real-time, enabling you to be lean and agile by treating our infrastructure as your own.

Stay In Control

Our web portal and API provides complete real-time control of our services enabling you to;

  • View chargeable calls in progress
  • Provision and reconfigure numbering
  • Configure advanced call routing
  • Add/Remove authorised hosts
  • Manage pre-paid balance and configure alerts
  • Configure fraud mitigation controls
  • Submit and manage porting requests
  • Track and manage your channel utilisation
  • Monitor call costs and traffic in real-time
  • Allocate SIP trunks and manage custom limits
  • Manage your account invoices and payments
  our API Documentation
  "datetime": "2014-02-30 12:34:35",
  "total": 1.164,
  "callcount": 105,
  "balance": 24.406,
  "percent_available": 0.25,
  "approx_seconds_remaining": 56838,
  "calls": {
    "1739": {
      "location": "UK - Fixed",
      "country": "GB",
      "total": 0.85,
      "callcount": 85
    "2303": {
      "location": "UK - Mobile - T-Mobile",
      "country": "GB",
      "total": 0.244,
      "callcount": 19
    "2761": {
      "location": "Spain - Mobile - Telefonica",
      "country": "ES",
      "total": 0.02,
      "callcount": 1
  "countries": {
    "ES": {
      "total": 0.02,
      "callcount": 1
    "GB": {
      "total": 1.094,
      "callcount": 104

Fraud Control


Other carriers like to talk about fraud, but do little to prevent it. They prefer to tell you what you’ve already spent, i.e. what they’ve already made a profit on.

At Simwood we perform over 200 checks per call, yet still have one of the lowest PDDs in the industry. We have fraud checks built into our architecture at every step, and use data from real-time attacks against our diverse honeypots to help protect you from fraud.

We are determined not to profit from your misfortune or that of your customers, so we proactively invest in detecting and preventing fraudulent activity.

Anyone can tell you how much you've spent after your platform has been hacked, but Simwood can help you SIP Carefully.

Built for Voice

Our geographically resilient, SS7 TDM interconnects and UK-wide numbering make Simwood the natural choice for carrier-grade termination and inbound call routing. In addition, we can also port numbers from most other providers and all UK mobile operators.

With variable and fixed price options, starting with minimum commitment, our wholesale voice plans are designed to appeal to everyone from developers and start-ups through to carriers.

Our Network

Wholly owned and operated by Simwood, 90% of traffic across our network is voice and video. On-net in eleven data centres for redundancy and availability, we have a pathological hatred of congestion - if a link is routinely more than 20% utilised we upgrade it. We believe we offer the network for RTC business.

Whilst our network exists first and foremost to give our customers the best quality of service possible for their voice and video traffic, we can also offer, full and partial IP transit, pseudo-wires, and co-location services.

Uncontended Peering

86% of our IP traffic flows directly over un-contended links to our peers.

We peer extensively over LINX and LonAP as well as extensively privately to ensure that traffic is handed off to other ISPs locally wherever possible.

Connecting to Us

If you are co-located with an established ISP, there is a very good chance they already peer with us. If you operate your own ASN we have an open peering policy and are present on route-servers of every IXP we're present at. We also welcome private peering or direct cabling for customers without an ASN, giving us the highest peering ratio amongst our contemporaries.


Not only do we own and operate the equipment in all of our sites, but we exert as much control over the links in between as possible. Within Manchester we own a dark fibre ring so control the traffic at the optical, layer-1, level.

Our London ring is mutually owned with other ISPs, so together we control the active optical layer on dark fibre leased from various owners. Nationally, we work with a diverse selection of peer ISPs for connectivity but ensure packet prioritisation and failover is always under our control and can happen in a matter of milliseconds.

Despite all this, we generally manage our traffic at layer-3 to ensure it enters and leaves the network as close to where it needs to be as is possible, avoiding unnecessary inter-city transmission of traffic.

The IP Network for RTC Business

Even if you do not use Simwood for voice termination, we believe we are the IP network for real time communications . We are unique in scaling our IP network specifically for voice and video, meaning you won't find cat photos or pornography clogging up our pipes.

Co-locating with us, or using us for your connectivity, could lead to shorter, more stable, paths to both your customers and your suppliers, over a network built for RTC. We prioritise voice and video traffic and recognise Quality of Service markings to ensure it takes precedence over any incidental traffic passed.

In addition, we can provide more mainstream ISP services in an isolated way including;

  • Pseudo-wires between metro areas
  • Metro area layer-2 connectivity
  • Metro area active-DWDM wave
  • IP Partial Transit
  • IP Full Transit
  • End-user connectivity at up to 10Gb/s i.e. for private connectivity or internet breakout
  • Co-location

Technical Talks

Upcoming Talks

Simwood is proud to be invited to give presentations at many industry events, please join us at one of these upcoming events and meet some of the Simwood team.

  • Astricon, Orlando, FL October 2017

Get Started!

Get started today with our Developer Account to explore our API and Portal, together with free credit to try our termination services for yourself..

Sign Up

Need More Info?

Any questions? Get in touch with our operations desk or sales team who will be happy to answer any questions you may have about our services.

Get in touch

Compare Our Rates

Enter a telephone number to compare our rates

Simwood eSMS Limited
Simwood House
Cube M4 Business Park
Old Gloucester Road
BS16 1FX
United Kingdom

0330 122 3000

Registered in England 03379831

Simwood Inc
301 Union St, #21445
Seattle, WA 98111