Question: In SMS protocol as per 3GPP standards, what does a `TP-User-Data-Header-Indicator (TP-UDHI)` value of '1' in the first octet of an SMS PDU signify about the structure of the `TP-User-Data (TP-UD)` field?
Option 1: The TP-UD field is empty, indicating no short message is included.
Option 2: The TP-UD field contains only a header without any accompanying short message.
Option 3: The beginning of the TP-UD field contains a Header in addition to the short message.
Option 4: The TP-UD field is compressed, requiring decompression before interpretation.
Explanation: According to the 3GPP standards for SMS, when the `TP-User-Data-Header-Indicator (TP-UDHI)` is set to '1', it indicates that the `TP-User-Data (TP-UD)` field contains not only the short message but also begins with a header, providing additional information about the message.