It was never clear what kind of business model twitter hoped for. Even bulk buyers of test services in europe would expect to pay 2p per message sent and that adds up quickly with the number of users and messages passing through twitter each hour. They have yet to force advertising on customers through either their website or text messages and like many other internet startups, they have been losing huge amounts of money while building up their user base.

The main function of twitter has been to allow people to send inane messages to their friends mobiles at inappropriate times. Imagine getting a message at 3am as you are woken up along with another dozen people just because one of your mates thinks it appropriate to text the fact that they've just thrown up in the back of a taxi. However, there have been really useful applications of the service, keeping people up-to-date with rapidly changing events in such a timely manor that they can act on that information.

Can this be replicated without twitter? Technically, yes, however the expense may be prohibitive. If you have 200 people signed up to receive your alerts during an action and you send out just 10 alerts that day, that's 2,000 texts. Assume a cost of 3p per text and that amounts to £60. It is possible to get sim deals with 'unlimited' texts for £25 or £30 per month but unlimited is bullshit in the context of telecoms marketing. In practice you can expected unlimited texts to actually mean 3000 or perhaps 5000 messages. Furthermore, the term and conditions of service normal preclude using the sim in a device attached to a computer, which would be necessary to facilitate the kind of system we are talking about. It's worth a try but it's hard to imagine it working as well and as conveniently as twitter.