CM Tooltip Glossary
21/12/2018

UDH (User Data Header)

User Data Header (UDH) is a binary structure which may be present at the start of a short message in an SMS. It does not contain any text but specifies how the message should be processed. Essentially it is a part of the SMS which tells the receiving handset what type of message is being sent. This is done to ensure correct SMS message delivery.