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Please Mr. Postman

Will you send a short message for me – well it turns out that is not so straightforward as you might imagine.

Have you ever thought about how an SMS gets from your phone, to its destination? It’s a lot more complicated that you might think.

Originally SMS was created with two main use cases. Firstly enabling mobile operators to send service status notifications to the phone, and secondly as a replacement for the pagers that many of us were carrying around at the time. Basically messages were designed to go from your mobile operator to you.

In the early days of selling SMSCs (the network element that manages the delivery of SMS) the business case was squarely based around sending voicemail notifications to consumers. Your mobile phone’s battery life was short, calling expensive – so phones were turned-off a lot of the time, and so voicemail was a very valuable service for consumer. In those days the business case for installing an SMSC was solely predicated around sending SMS to let you know you had a new voicemail waiting for you. That SMS would not only tell a consumer that a message was waiting for them, but also on average the SMS would generate 1.5 voice calls. One call to retrieve the voicemail, and 50 percent of the time another to ring back the person who left the message.

All very simple, just one direction and messages never left that particular network.

Fast-forward 20 years and it is all very different. Not only can you now send messages, those messages can go to other networks not only in that country – but also now across the world. They can even go to networks that aren’t based on the GSM technology.

And perhaps the biggest change – they cope with MNP (mobile number portability).

When SMS was created it was decided to use the MSISDN to route SMS messages. The MSISDN (or mobile telephone number to you and I) seemed an obvious choice. The first few digits tell you the country – so +44 tells you that it is a mobile in the UK. And the next 3 or so tell you which mobile network it belongs to - so 775 would be Vodafone. So with this information you can route the SMS to the correct network for delivery.

This method worked fine, but then came MNP. Now when you change mobile networks you can take your number with you. So how can you deliver a message, when you don’t know where it has to go? Imagine a world where when you move house you took your address with you – how would your postman find you to deliver your post?

On top of this (technical) complexity you also have to manage with the commercial aspects with dealing with the 1000+ mobile networks in the world.

So how do mobile operators cope with connecting to all the operators in the world? In general they don’t.

Most operators will connect (directly) with 500 or so other mobile operators. Which means that some destinations you try to send an SMS to are unreachable. And in turn means failed messages for consumers, and a loss of revenue for the operator.

My colleagues over in SAP Mobile Services have created a very clever solution of how to ensure the messages can get to more destinations that ever before – with a service called SAP Intelligent Hubbing 365. And Vodafone Czech Republic is the latest operator to join the service.

You can read more about the announcement here.