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Monday, 25 March, 2002, 18:00 GMT
Mystery of missing 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.
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.
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.
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.
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.
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.
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.
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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! :)
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.
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
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
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!
No problem with text messages, but I did have an e-mail sent in August 2000 that arrived 18 months later in January 2002.
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