登录后主页给了received sms计数器，链接到的帮助页面写了这堆：

There is a weekly limit of 250 messages per week on the UK long code
There is no limit on incoming updates to Twitter from your mobile phone, however, you’re limited to 250 SMS messages from Twitter to your mobile phone if you use our international number

How does it work?
Each week you’re allotted a total of 250 SMS updates per mobile phone, when using the UK long code. We measure the week from Sunday to Sunday. When you’re close to your 250 message limit via Twitter on your mobile within a week, we’ll let you know via text message. We’ll also place a reminder on your Twitter homepage.

每周250条短信总量限制，Sunday to Sunday。

还有公开通告里不详的: direct message这种不公开消息还ok的，还没发现有漏。飞信这几天不太好登，替代下还不错哈！但，普通更新和@username的ms是24小时限制接收1条，当然说的是从同个人咯~ :( 这就比较郁闷了，只能采用其它方式跟踪…

updated: 不是如上所说。又试了n次，ms只有超短的更新才能短信通知到。