Top Up


The Top Up mode helps improve the connectivity for consumers by seamlessly ‘topping up’ their xDSL with 3G/4G.

Deploying FTTx isn’t always economically viable for many operators due to the cost of civil works, time and effort required, and the reducing margins on fixed broadband. By allowing xDSL and 3G/4G to be brought together in an intelligent way, significantly faster speeds can be delivered immediately with little cost. This may delay the need for FTTx investment for, but, also, the Top Up mode can help show where the demand for faster speeds are.

In addition, many operators are under increasing pressure from government and regulators to address areas of slow broadband.

How It Works

The software is installed on a new or existing device in the customer’s home and uses a 3G/4G source to aggregate with, in an intelligent way.

Top Up uses the xDSL line’s capacity first, then only bursts into cellular when it deems it needs to. This reduces mobile usage whilst still offering a responsive experience for customers.

A maximum aggregate speed can be configured for each customer e.g. 16Mbps, so that operators can offer different tiers xDSL / mobile packages.

Our Hybrid app allows the smartphone’s 3G/4G connection to augment the xDSL broadband, without the need for tethering or any re-configuration of the device.

The smartphone connects to the home Wi-Fi network as normal. It then searches for the Top Up router and registers itself as available to use, if required. If the home broadband goes down, or there is a need for extra capacity, the Top Up feature rapidly determines which smartphone’s 3G/4G connection is the best one to use.

The user-interface has been developed to make it simple for customers to see what’s going on, decide which devices are able to benefit from the increased speed boost as well as configure inbound port forwarding services.

The Hybrid app running on a customer’s 3G/4G smartphone is the most common way of accessing the mobile network. However, Top Up can be used with a variety of other connectivity options;

  • Embedded; where an LTE modem is embedded within the CPE itself
  • Dongle; allow a variety of 3G/4G USB LTE dongles to be plugged into the CPE
  • Mi-Fi; connect via Wi-Fi to a hotspot to provide an always-on 3G/4G connection

Top Up supports all regular traffic types (TCP, UDP, ICMP, GRE, PPTP, L2TP, IPSec) which is then sent via an aggregation server. Therefore, the IP address and port forwards remain the same. Top Up is an Over-The-Top solution which can operate across multiple smartphone service providers.

Some mobile operators are starting to hit the limitations of maximum number of UE’s per mobile sector. As existing UE’s are utilised in the app model, rather than new UE’s having to connect, this can help reduce mobile base station optimisation and re-configurations.

Router Options

Integrated solution

The software stack can be ported to most CPE devices running Linux 2.4.19 kernel or newer. It is a user-space application, doesn’t require any kernel modules that aren’t installed as standard and, depending upon complexity, can be ported rapidly.

Common processors such as x86, mips and ARM are supported and our application typically requires 1.5Mbytes RAM and approx 700Kbytes of flash storage. The kernel version, RAM speed and CPU speed will determine maximum throughput.

Supplementary device

Where it isn’t possible to port the software stack to your existing CPE; either because there are too many variations of CPE in the field, or there isn’t enough RAM, CPU or flash to accommodate the software stack, a patented plug & play router is available.

The plug & play router is a low-cost, small (42mm x 42mm) device which plugs into a free ethernet port on the back of the customer’s xDSL router. It effectively then becomes the default gateway and typically requires no configuration on the router or customer devices.

Its very low power consumption means it can be powered from the free USB port on most home routers, eliminating the need for a separate PSU.

The device does not come with a 4G modem or SIM slot, but can either leverage the Hybrid app running on smartphone(s) in the house, connect to a Mi-Fi device via the in-built 802.11N Wi-Fi or, depending upon version, via the USB port to connect to an LTE dongle.


The retail solution has been well received in the media, with coverage from both the BBC and Financial Times.

This solution is currently on sale at retail in the UK and can be purchased from the dedicated website.

More Information

Please contact us for more information about our Top Up solution and how it would best fit your business model. Please visit the end-customer focused website