Application Port Numbers in SMS
On this page software developers can learn how to use
application port numbers in SMS using the Ozeki SMS software.
Application port numbers can be used in SMS
messages to deliver a particular SMS to an application on a mobile phone.
In most cases, applications on mobile phones are developed using Java technology
The application port addressing feature of SMS messages allows specifying
a source port and a destination port number for an SMS message (Figure 1).
Figure 1 - Sending a message to a particular application
The Ozeki SMS software supports the setting of both
the source port and the destination port. You can perform this by putting
the source port number after the sender phone number, and the destination
port number after the receiver phone number. Put a colon between the phone
number and the port number, without using any spaces.
Look at the example SMS below:
Message: Hello World
The source port number in the example is 1128, and the
destination port number is 3224. The port number has to be specified
as a decimal value. This value can range between 0 and 65535. The
application port number information is transmitted in the user data
header (UDH) of the SMS message.
For example to send a message to the hexadecimal destination port 3333, with
the following user data header (UDH): 06050433330000, you should send a message
to phone number: 13107. The reason for this, is that the decimal port number 13107
will be converted to the hexadecimal value 3333.
To check if your outgoing message contain a port number, you can enable low
level communication logging in the GSM Modem configuration form. After low
level communication logging is enabled, you will see the PDU, that is
submitted when a message is sent. The should contain a user data header field
(UDH), that includes the port number.
If you send the message: From: +44777888:1128, To: +441234567:3224, Message:
through a GSM modem your message will contain the following user data header:
0605040C980468 (Figure 2).
In this PDU, the 06 is the length, 05 means port number, 04 means data length,
0C98 is the destination
port, that has a hexadecimal value of 3224, and 0468 is the source port, which
has a hexadecimal value of 1128.
Figure 2 - User data header in PDU
This port number functionality is available from all
Application Programming Interfaces (API)
with the help of modifying the telephone numbers.
If you use a GMS modem, please note that port numbers work only if PDU mode
is configured. (PDU mode is
the default configuration)
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