Net Results: We've all been there: fuming over the Case of the Missing Text Message, writes Karlin Lillington.

There are two standard scenarios. You've sent a message and your friend/colleague/significant other/boss insists that no, absolutely, it did not arrive, and you are officially an eejit/a betrayer/in the doghouse/fired.

Or else, you were sent one by your boss/colleague/significant other and you insist that no, absolutely, it did not arrive, and you are officially an eejit/a betrayer/in the doghouse/fired because you didn't show up/make the meeting/get the pint of milk on the way home/give the presentation to the board.

Well, now you have a formal excuse, backed by research in the US (so it's got to be true).

A new study this week states that around 7.5 per cent of all text messages sent in the US get lost and never arrive.

The level at which the messages go AWOL depends on the network you're using as well. AT&T Wireless did pretty well, with 95.5 per cent of messages sent to other networks, and 97.8 per cent sent within its network, arriving into a phone message inbox somewhere.

Verizon topped the list as far as performance in receiving messages, scoring 95 per cent, while AT&T trailed fractionally at 94.8 per cent. Bottom of the list was Deutsche Telekom's T-Mobile, where only 86 per cent of messages sent to another network, and 87 per cent of messages sent to another T-Mobile phone, reached their destination. T-Mobile phones received 92 per cent of messages sent from other networks.

I can't imagine the case is much different here. There have already been much-publicised cases to support this. For example, a British operator admitted that a percentage of text messages sent as part of a competition never arrived. In that case, the operator said the network was simply unable to handle the volume of messages. Uh-huh.

But that's not the case in the US, where SMS is only just beginning to take off. Americans have worked themselves up to keypadding out a billion messages a month. Europeans do that in a day. The study estimates that even at those relatively low US texting levels, millions of SMS messages are lost in the system each month. Imagine the situation in Europe.

I know that I routinely do not receive texts someone supposedly sent and that my intended recipients don't get mine. And I regularly get texts hours after they must have been sent. Nonetheless, people increasingly assume an SMS is the equivalent of a phone call or an e-mail.

Neither communication method is faultless, but they're much better than SMS. Most of the time, a phone call in particular is far more appropriate anyway. E-mail is bad enough as an inappropriate substitute for certain types of polite, courteous or awkward phone calls that someone is too idle or inconsiderate to make.

I am thinking of the example of a large computer company which, after taking over a friend's small company, used e-mail to tell people they no longer had jobs, even after those people had gone through the full face-to-face interview process. The human resources person (such as she was) believed that without human contact, these people were easier to dismiss, vague statistics rather than, er, human resources. Extraordinary.

Yet SMS is creeping in as an even more brief and outrageously feeble substitute for voice communications, even in cases where a voice conversation is preferable, even demanded. You've probably read the occasional story about the woman fired by an SMS, or the guy whose wife dumps him via same. Not only do you not have to speak to the person involved - you only have to cope with the tiny little character-limited screen of a mobile. What a relief! You can dispense with having to think about how to phrase that awkward message or about being considerate. There just isn't enough room. H8 2 TELL U BUT U R FIRED. CLN OUT YR DESK MON.

So here are my rules for proper texting etiquette.

Text is great (whoops - GR8) for quick, casual messages, or to pass on a snippet of information that isn't time-dependent, or just to have fun, and especially to carry on a pleasant little flirtation (but please, turn off the notification sound - you'll drive everyone around you crazy with a flurry of ringtones announcing your mots d'amour).

But please: it is not OK to rely on a text message when a key appointment, meeting or date is involved, or a courtesy message. It's especially not OK to offer a thank you for, say, a dinner party or kind favour received, unless the person is a really close friend and you'll be talking to them anyway regarding same. If someone spent hours and probably days preparing a great evening for you, surely they deserve a little more of your time than a 20-second thumb workout on a mobile keypad?

Nor is it OK to check by SMS if you are supposed to be somewhere where other people are relying on you to be.

Or to ever, ever offer condolences or deep apologies. Or to fire someone/announce your divorce (unless you are being deliberately cruel, of course, which is allowed in extenuating circumstances).

For ease of remembering, this is the basic rule: Your Mother Is Always Right. Translated, that means that technology doesn't let you off the hook where courtesy is concerned.

A handwritten note is still better in some circumstances than a phone call (or in addition to a phone call). A phone call is de rigueur in any situation requiring certainty that a message has been received or given, or where any sort of politeness or consideration is demanded.

On the other hand, if you want the perfect excuse just say the message you definitely, oh, DEFINITELY sent or were to receive must have been among those 7.5 per cent. You truly didn't realise you were needed back in the office from your long lunch.

klillington@irish-times.ie

Karlin's tech weblog: http://radio.weblogs.com/0103966/