I'm a big fan of micro-blogging service Twitter. It's one of those hard to explain, great to use services that just need to play with to get going. Basically, think Facebook status but updatable via web, sms, IM and apps and receivable via web, sms, IM and apps. Well, in the US anyway.

You see Twitter hasn't been able to do deals with all the world's mobile carriers and has therefore shut off the receiving of SMS updates everywhere except Canada, India and the US. As the startup has yet to go public on a business model it's keen to conserve the cash on paying for all those SMSes.

Personally, i'm not so bothered. If you use the service to communciate with other people, you turn the SMS updates off after you've added about 20 followers otherwise your phone never stops going. The main people it's harming is the ones who probably just use it for free SMS updates from newsfeeds that they're interested in. And you could say that their use probably isn't at the core of the service.

What this does show is that it's always difficult to cease a service that you've been providing for people, even if it's free - there's bound to be a backlash. The interesting thing with this one is that, reading the Get Satisfaction page on the issue, the main loss is actually notifications of direct messages and the fact that there wasn't any warning about the service ceasing.

Direct Messages are messages that are sent to you directly rather than publicly - it's normally from people who've seen you ask a question who aren't neccessarily close enough to have your mobile number, or who can easily send them (probably through a twitter client). It would be interesting to see the percentage of SMSes that are from these direct messages, I would imagine it's less than 1%, but its valued hugely by the regular user base.

There's also some desire from users to pay for the privilege of receiving messages. In the UK reverse billed SMS is very easy to setup - if there's demand why not do it? It might even pay for all those direct messages.

It's another good example of the importance of having a conversation with your users on what's happening. Whilst blogging or emails aren't going to reach everyone, they're likely to reach the power users who will cause all the fuss. There even might be some suggestions that make the final transition a bit healthier.