Working SIMs

We had three interesting confirmations of our mantra that “Not all SIMs are the same” this week. One was in regards to an old customer of ours who had gone through a cycle of alternative suppliers for the last five years. Luckily they also retained our estate so were happy to take our samples for a new project that they have been planning for some time. While they all looked good in the bench tests when it came to field trials only one set worked, the ones from Mobius.  In this case the term ‘work.’ is simply defined; the data was sent and received from multiple European connections in a repeatable manner.

Often though ‘work’ is more complex.

In one case the client had two Vodafone SIMs provided by two different VAR’s side by side in a door access system. In one unit the Vodafone SIM worked and in the other it didn't. Both were connecting successfully through a private IP network and were reported by both suppliers as ‘working’. But one door opened and one door didn't.

It turned out that the data going through one private network was taking around 800ms to deliver its message while the Mobius SIM, in the same kit, on the same network, was delivering the data in around 80ms. We can speculate as to why but the key here is that although both providers could say that their solution did ‘work’ only one was fit for purpose.

The final case, actually from last week, was regarding availability. This can be measured in lots of ways and has lots of parameters but put simply- if a customer needs to know where something is, continuously in real time then the system can only be described as working if it is sending the data, sending it quickly and available continuously.

This last parameter is really tough. You will have seen elsewhere that we delivered 99.995% availability for Slough County Council and their traffic light system (SCOOT).  But this application was a moving one in a huge variety  of environments from one end of the UK to the other. Apparently as a result we had sporadic but regular 3 minute gaps in network. In terms of the customer expectation it didn't ‘work’ despite meeting the first two criteria.

I’m pleased to say that with a lot of hard work and strong co-operation by all parties we now have eliminated those gaps. The SIM and indeed the whole system around it now ‘work’. A process I hope to detail in a case study soon.

In all three cases though if the parties involved had said that the reason for failure was due to a faulty SIM or that “it must be the network” and shrugged their shoulders then the systems our clients were trying to deploy would never ‘work’. Which is why a SIM can’t just be a SIM.

 

Written by Douglas

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