Skip to main content

A Discussion of Network Performance

Image of city tower block at night with 1' and 0's scattering across.
Share This Article

Why Multi-Network?

IoT SIMs can be supplied in many variants from single network, single country to global, multi-network offerings. Multi-network SIMs are typically a little higher in price than single network solutions, not as widely available and you will often find that network providers will be keen to supply a SIM that works on their network only. Therefore, the question arises, why pay more for a multi-network SIM? To answer this question, a simple understanding of how a mobile network performs day to day is essential.

The Nature of Dynamic Networks 

Many people incorrectly believe that mobile networks offer a static service meaning that the service is consistent in terms of availability, quality, and performance at different locations and at different time of the day or week or month. People often think a mobile network is like a light-bulb in that it either works or it does not, and when it is perceived to be working will have a constant level of performance. This is not the case and the following basic principles will attempt to explain this.

Mobile Network – Building Blocks 


The first building block of a mobile network is a cell. Cells are configured by mobile operators to address the specific needs of where they are located. For example, a cell on the edge of a densely populated area will more than likely be
configured such that the coverage footprint is more dominant in the direction of the population rather than out into open countryside. This is achieved via a number of factors including the actual direction the infrastructure is pointed
towards as well as other remotely configured factors such as the power of the transmitter. Therefore, even before we consider the impact of what the day-to-day usage of the cell is, it can be seen that all cells are clearly not the same or are designed to have the same capabilities. The next factor to consider is what happens when the cell is in use.

Mobile Network – Cell Dynamics

Same cell – different performance: 

Under normal conditions the performance and availability of the network differs based on the time of day and indeed from one day to the next. It is quite possible, therefore, that the performance of the network at a certain time on one day will not be the same as at the exact same location the next day. Many of us have tried to send a message or a picture from a concert or sports stadium without success or with a significant delay on the receiving side. If you went back the next day without the crowd, you would almost certainly not experience the same network
congestion issues.

Factors which can impact performance are many and varied such as maintenance, outages, congestion, sleeping cells, extreme weather, and physical structures such as construction and trees can block or reduce signal strength. Also, longer term, network operators are always looking to optimise the network and are regularly adjusting the parameters of the cells and this can mean that perfectly good coverage on one day at a particular location can become permanently reduced or degraded coverage from the next day forwards due to network reconfiguration or
optimisation work.

Network Services & Coverage

Technology availability:

A mobile network actually delivers a number of separate services to the subscriber (2G, 3G, 4G and soon 5G) and these can have different coverage footprints. Meaning, that in any particular location you can have a scenario where you can make phone calls, but the internet experience is slow, or vice-versa. For example, in one instance, this could be because there is no 4G present. The absence of 4G itself could be due to there being simply no 4G coverage at all for that cell and area or that there are other factors in the area that are affecting or limiting the existing 4G service. This problem can affect any mix of the available services; with another example being that there is a detectable signal, but not enough to allow certain types of messages or signalling to be sent or received.

Core Networks and their Eco-Systems 

Core Networks and Device Intelligence:

It is also important to consider, however, that mobile networks are complex ecosystems which require interfaces within each operator’s core networks, partner technologies and systems and shared networks. Failures in one of these systems can also cause problems, which to the user may be perceived as localised to themselves. This, however, can be a representation of a degradation or loss of service within a core network or system interface. One that might only be a short-lived or temporary state, or an early symptomatic representation of a wider or burgeoning problem; or one which is more prolonged, requiring further monitoring, diagnosis and remedy. In these cases, problems with a single operator’s core network can be circumnavigated by connecting to another network if the device is intelligent enough to detect a loss of end-to-end connection via that individual network and to switch networks accordingly.

Multi-Network Services & Coverage

Multi-network capability:

All these factors affect all operators but thankfully not in the same place or at the same time. Some operators will have greater capacity in one area than another etc. Therefore, it is far more than likely in a country served by multiple network operators that the absence or failure of one network will still leave all other networks unaffected and available for normal use.

Coverage Maps:

Some IoT companies will look at operator coverage maps and determine that where they want their devices to operate, the coverage looks very good and therefore a single network SIM is all that is required. Operator coverage maps are generally owned by the marketing functions of the mobile operators and are by no means real time. Often, they are updated only every few months and are supposed to be a theoretical picture of the ideal coverage. Putting aside the earlier points about the hypothetical experience is versus what is actually experienced by customers day to day, they are not a reliable picture of day-to-day network availability or experience.

Network Selection 

The role of the SIM in switching between networks:

Having potentially decided that a multi-network SIM is a more robust and resilient solution, it is important to understand the role the IoT device plays in conjunction with the SIM. There is quite often a perception that the SIM itself has the intelligence or capability to switch networks. This is not correct. A SIM card is essentially a very small, but highly secure piece of memory with a number of data strings and codes programmed on to it. It is when these details are presented to the mobile network, the network will know what to allow in relation to the service.

For example, data bundle, network availability, geographic restrictions etc. A multi-network SIM, therefore, has the theoretical capability to connect to all networks available, if multiple network usage is enabled as part of the tariff/bundle. It will, however, be the IoT device logic and modem messaging/configuration that governs how or why this switch occurs.

How a device behaves in a multiple network environment:

At its most basic, an IoT device will behave like a smartphone. There will be a very simple signal strength measurement similar to the 5 bars we see on the top of the display on commercial smartphones and when the signal strength falls below a threshold predetermined by the device firmware, the device will instigate a network search. The device will scan the remaining available networks and connect to that which has the strongest signal. However, as discussed in the earlier section “Technology availability”, there are different things that determine the availability
of different services (the 5 bar concept on the phone is really a measure of the ability to make or receive calls). Therefore, this does not really relate to the quality of the data signal, which is what tends to matter most in the majority of IoT applications.

Smarter devices will have more sophisticated logic which may include the ability to measure the quality of the data signal or some key metric relevant to the service. Some devices may also have some degree of flexibility in deciding at what point the device triggers a new network search. However, in all of this, the SIM is only really acting as a passport to the network and does not have any intelligence or role in the actual decision to switch networks or search for a new network. Rather, it provides the important capability for the device to successfully authenticate on a number of networks and be placed as a visitor on the Visitor Location Register of a local network and be correctly billed to the hosting party who originates and manages the SIM. 

In summary:

The Benefits of Multi-Network SIMs: 

Whilst there is a place for a single-network IoT SIM, the multi-network SIM has several benefits which make its cost of ownership and return on investment much stronger than the single network offering:

  • A multi-network SIM is as close you can get to an “always on” connection
  • Due to how mobile networks are deployed and run, operators will have outages and gaps in coverage at different places and different times of the day. As such having a solution that can use multiple networks, limits this problem.
  • There is no need to perform any sort of network survey at deployment locations as the overlay of 3 or 4 networks means there will be good quality coverage available.
  • Any service based on multi-network SIMs will have a much higher availability and hence much greater level of satisfaction with the end user.
  • Organisations can offer or comply with SLA requirements from their customers as they know the network availability is almost 100%.

About Caburn Telecom: 

Caburn Telecom partners with several global Mobile Network Operators, for the supply of SIMs and data into worldwide IoT markets across every continent. Caburn Telecom delivers a vision of highly engineered solutions to the highest levels of customer service catering for those enterprises for whom secure and resilient M2M/IoT connectivity are business critical elements. 

Caburn Telecom is headquartered in the UK with offices in the European Union, Asia and the United States. We are able to offer different solutions to meet all requirements from cost effective single network solutions to highly flexible multi-network offerings across a range of our network partners. This can be provided via traditional plastic SIMs or eSIMs and on the full range of network technologies (2G, 3G, 4G, NB-IoT, Cat-M1 etc.). 

Our global reach gives us access to over 600 mobile networks across 200 countries worldwide. We are able to offer this truly global reach via our set of major network partners including EE, Vodafone, Telefonica (O2), Three, KPN, MT, Verizon etc. All our customers benefit from the value add of Caburn Telecom’s key foundations of our commercial model, our Insight SIM management platform, and our support