我住的地方（丹麦哥本哈根）有一家出租车公司，当您订购的汽车即将到达时，他们会向您发送短信。
这些短信与我在 iPhone 上收到的任何短信不同，它们全屏显示，并且不会保存到短信应用程序中。请参阅此屏幕截图：
一旦您按下“关闭”，消息就会完全消失。短信应用程序中没有它的踪迹。
我认为这样做的能力可能在某种程度上对应用程序有用。对于超级重要的事情，可能会提供而不是定期的推送通知。但最重要的是，我很好奇想了解正在发生的事情。
Where I live (Copenhagen, Denmark) there is a taxi company which offers to send you an SMS when the car you ordered is about to arrive.
The SMSs are unlike any I have received on my iPhone in that they appear fullscreen and are not saved to the SMS application. See this screenshot:
As soon as you press "Dismiss" the message is completely gone. No trace of it in the SMS application.
I was thinking that the ability to do this could be useful for apps in some way. Perhaps offered instead of a regular push notification for super important things. But most of all I am curious to learn what's going on.
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Is this a regular SMS or some sort of cell network alert?
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How can these be sent? Is it content formatting which triggers this special display or is it a protocol feature?
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How would they appear on other phones?
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If it is not a regular SMS but some sort of network alert would it be possible to send one to a 3G-enabled iPad?
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在短信前加上
*go前缀。请参阅此链接！
请务必查看 此链接（链接现已失效，因此请查看archive.org 版本）也如此，因为发送它们可能会产生额外费用。经过研究，只有海外（非美国）的 GSM 提供商可以做到这一点。
Prefix your text messages with
*go.See this link!
Be sure to see this link (link is now dead so view the archive.org version) too as it may cost an additional charge to send them. After research only GSM providers over seas (not in the US) can do this.
我刚刚写了一篇关于这些 0 类或“flash”消息的博客文章 此处。它们现在在 iOS 7 中看起来略有不同：
SMS 规范 对于 0 类消息有这样的规定：
我进一步研究了这些技术细节，结果发现该类是使用 SMS-DELIVER 和 SMS-SUBMIT 的“数据编码方案”(DCS) 字段的最后 2 位来设置的 协议数据单元。 DCS 字段是单个八位位组，其用途根据位 4-7 的值而变化。在位 4-7 设置为 00xx 或 1111 的情况下，可以指定消息类别。
在前一种情况下，位 5 指示文本是否被压缩，位 4 指示是否已指定消息类别，位2 和 3 指示字符集，位 0 和 1 指定类别（如果位 4 等于 1）。因此，例如，00010000 (0×10) 将表示使用 GSM 7 位默认字母表的未压缩 0 类消息，而 00110100 (0×34) 将表示具有 8 位编码 UD 字段的压缩 0 类消息。
I've just written up a blog post on these class 0 or "flash" messages here. They look slightly different now in iOS 7:
The SMS specification has this to say about class 0 messages:
I had a look into the technical details of these a bit more and it turns out that the class is set using the last 2 bits of the "Data Coding Scheme" (DCS) field of the SMS-DELIVER and SMS-SUBMIT protocol data units. The DCS field is a single octet, the use of which varies depending on the value of bits 4-7. A message class can be specified in the cases where bits 4-7 are set to either 00xx or 1111.
In the former case, bit 5 indicates whether or not the text is compressed, bit 4 indicates whether a message class has been specified, bits 2 and 3 indicate the character set and bits 0 and 1 specify the class (if bit 4 is equal to 1). So, for instance, 00010000 (0×10) would indicate an uncompressed class 0 message using the GSM 7 bit default alphabet and 00110100 (0×34) would represent a compressed class 0 message with an 8 bit-encoded UD field.
它称为 Flash SMS，也适用于其他手机。来源：http://en.wikipedia.org/wiki/Short_Message_Service#Flash_SMS
It's called a Flash SMS, and works on other phones too. Source: http://en.wikipedia.org/wiki/Short_Message_Service#Flash_SMS