Sending a concatenated SMS using a User Data Header. One way of sending concatenated SMS (CSMS) is to split the message into 153 7-bit character parts (134 octets), and sending each part with a User Data Header (UDH) tacked onto the beginning.

What is PDU SMS?

(PDU stands for Protocol Data Unit.) The mode that a GSM/GPRS modem or mobile phone is operating in determines the syntax of some SMS AT commands and the format of the responses returned after execution. Below are the SMS AT commands affected: +CMGS (Send Message)

How can I send SMS more than 160 characters?

When you send an SMS Message longer than 160 characters, the message will be concatenated and split into 153 character chunks. The 1st 7 characters of each message are used to instruct the carriers and your handset to concatenate the message and re-build it into one fluent long message upon delivery.