PDU 7BIT编码程序，目前，发送短消息常用Text和PDU(Protocol Data Unit，协议数据单元)模式。使用Text模式收发短信代码简单，实现起来十分容易，但最大的缺点是不能收发中文短信；而PDU模式不仅支持中文短信，也能发送英文短信。PDU模式收发短信可以使用3种编码：7-bit、8-bit和UCS2编码。7-bit编码用于发送普通的ASCII字符，8-bit编码通常用于发送数据消息，UCS2编码用于发送Unicode字符。-PDU 7BIT encoding process, at present, commonly used to send short messages Text and PDU (Protocol Data Unit, Protocol Data Unit) mode. Send and receive SMS Text mode using a simple code to achieve them is very easy, but the biggest drawback is that the Chinese can not send and receive text messages　and SMS PDU mode only supports English, but also send text messages in English. PDU mode send and receive text messages you can use three kinds of coding :7-bit ,8-bit and UCS2 encoding. 7-bit encoding used to send normal ASCII characters ,8-bit encoding used to send data messages, UCS2 encoding used to send Unicode characters.