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dot life Monday, 25 March, 2002, 18:00 GMT
Mystery of missing text messages
Ocean's Eleven, one movie promoted with text messages - Image Net
Planning a heist? Best not rely on text messages
Ever "lost" a text message? Ever claimed not to have received one when you did? The fact is, text messages go missing. BBC News Online's technology correspondent Mark Ward investigates.

Mobile phone text messages are the mayflies of technology.

Like adults of the insect order Ephemoptera, they have a notoriously short lifespan, three days typically, and leave little evidence of their passing.

And often their prospects for survival are as uncertain as mayflies that choose to dance on the surface of a well-stocked trout stream.

The reason is that text messages are a victim of their own success. According to the GSM Association, the mobile phone industry's trade body, 30 billion a month are now being sent.

No guarantees

This is far more than was ever envisioned when the Short Message Service (SMS) was developed, said Pamir Gelenbe from text marketing firm Flytxt.

"Nobody ever thought that bored commuters would be sending messages to Radio One DJs," he said.

It's becoming increasingly unacceptable for those messages to perhaps be delivered, or perhaps not

Andrew Bud, mBlox
Certainly, the phone companies did not predict the boom and, as a result, their technology often cannot cope with demand.

No-one has figures on how many SMS messages go astray, largely because before now it has not been possible to track them.

Perhaps for the same reason, none of the firms running ad campaigns via text messages have guarantees from mobile operators on how many messages will get through.

After all, said Mr Gelenbe, it would be hard for the operators to give a guarantee for something they could not control.

Choke points

There were many places in the mobile network that could kill messages, said Andrew Bud, managing director of SMS transmission company mBlox.

The first, and most important, is the hardware in every mobile network that co-ordinates the sending of text messages - the SMS Centre.

When you send a text message, your handset talks to the SMS Centre and asks it to pass on your prose.

Cigarette, PA
Text messages have been used to spread the anti-smoking message
The first SMS Centres were simply too small to cope with the volume of messages passing through them, said Mr Bud.

The second choke point is the part of the mobile phone spectrum over which the messages travel. They share the same part that controls the starting and stopping of a phone call.

Setting up a call does not take up much capacity and passing on an SMS a little more, but with enough text messages the available room can get used up quickly.

When the space is used up, the SMS Centre goes into frenzy.

"If it finds that the telephone lines are blocked, it tries again and again and again," he said.

This can cause huge problems for a mobile operator because it can mean that customers suddenly cannot make voice calls because attempts to re-send SMS messages have sucked up all the available capacity.

Buffer zone

Finally, there are the buffers, waiting rooms essentially, on the base stations that make up a mobile network.

When a message is being passed on, the SMS Centre contacts the base station nearest your handset and asks it to contact your phone and pass on the message.

However, if the buffer on a base station is full then it will not accept any more messages and the SMS Centre will have to try later.

An SMS Centre would typically try to re-send a message 40-50 times over the three-day life span of a text message, said Mr Bud.

Further problems arise as companies and media organisations start to use SMS to advertise or to get feedback from their audience.

Cadbury's chocolate bar, BBC
Cadbury's ran a competition using text messages
"Mobile marketing can generate huge volumes of messages in a short period of time," said Simon Holmes of Logica, a technology firm that makes SMS Centres.

Few networks are built to cope with the huge spike in traffic this can cause.

Some mobile advertising firms bought SMS in bulk from operators and sent them out in one mass, instead of at a rate the network could handle, said Mr Holmes.

Other problems can be caused by the device receiving requests for a radio show or entries for a text competition simply not being able to cope with the huge numbers of messages turning up.

"Where there are problems, operators are getting swamped with traffic from applications that they have not been made aware of," said Mr Holmes.

As a result messages can get caught in the system and sometimes operators are forced to trim the queues to cope.


When it was only consumers sending messages to each other, operators did little to improve the way they handled messages. After all, said Mr Bud, they had already billed the client for their message so they lost nothing by it going astray.

But, as the cost of sending messages rises, as messages get longer and it becomes possible to use SMS to send expensive things such as images and sounds - reliability will become much more important.

"It's becoming increasingly unacceptable for those messages to perhaps be delivered, or perhaps not," he said.

Now, some operators are splitting their SMS messages out of the mobile network altogether to ensure they can be sure they will get through.

Also starting to appear are pieces of hardware that can cope with the avalanches of messages that radio or TV shows can generate or that advertisers send out.

Ever lost a text message? Ever claimed you've never received a text message someone's sent you? Let us know using the form below.

You can also send your message by SMS - send them to the number 07736 100100.

Every Monday looks at how technology has changed our lives, and more importantly how we would like to change our lives. Let us know your views, also using the form below.

Your comments:

If your phone has it, switch on delivery reports. You can see delivered or pending messages.
Jonathan Datchet, UK
[Jonathan becomes the first person ever to send a text message to Congratulations!]

Let's be honest, I think we've all pretended we've not received an SMS, or by the same token, not answered a mobile call when we know who is calling. Just because we have the technology, doesn't mean I want to be forced to use it if I don't want to, particularly if the girlfriend is looking for me when I'm in the pub! :)
Simon Gray, UK

I use SMS for business and also personal reasons. There have been many occasions when I have sent (or have been sent) a text message and it has not gone to it's intended destination. Seeing as we have to pay for every text message we send, we should legally be refunded the cost of every undelivered message. As always, it's the consumer that suffers.
Simon, London, UK

I use a lot of SMS, in fact I'm sending this to you by SMS and i&stringint(var) too long: reset failure in device SMSstackFF02
Clive, UK

There were frequent rows in our family about text messages, people not replying, not getting messages etc, so we now have a family text etiquette. For instance, we don't reply to jokes, we always acknowledge the receipt of important facts, and if mummy texts you she typically wants you to text her back. Those are the basic rules, so we know that if an important text is not acknowledged you must assume that the recipient did not get the message. It has reduced the number of arguments, but until the technology is more dependable the obvious rule of thumb is just DON'T rely on text for very important messages
Max, N Ireland

The phones in the UK seem like square wheels to the phones we have out here. When sending SMS to busy stations the phone will inform you and ask if you wish to store the message so it can be sent when space is available. No problems out here for bulk advertising either, apart from the advertising itself...You'll be begging to have the jammed stations back!
James, Japan

No problem with text messages, but I did have an e-mail sent in August 2000 that arrived 18 months later in January 2002.
Debbi, US

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Disclaimer: The BBC will put up as many of your comments as possible but we cannot guarantee that all e-mails will be published. The BBC reserves the right to edit comments that are published.

Weely guide to getting buttoned up

See also:

14 Feb 02 | Business
08 Feb 02 | Science/Nature
17 Jan 02 | Science/Nature
24 Jul 01 | Business
21 May 01 | Wales
18 Dec 01 | Science/Nature
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