This guide provides you detailed information
on how to cancel an SMS text message after it has been sent to the SMS center
(SMSC) but it has not been received by the recipient. This functionality can be
achieved by cancel_sm service that is first available in 3.15.8 version of Ozeki
NG SMS Gateway. Follow the guide below to adopt this service successfully.
If you send out an SMS message from your database with the help of Database
user of Ozeki NG SMS Gateway you need to insert a record into the database.
The database user checks the database and it sends out the SMS text message to
the SMS center (SMSC). From the SMSC you will receive a report about the fact
that the message arrives at the SMSC. This report contains the callback ID of
the message. When the report is received the Database user updates the message
status to Sent and insert the callback ID into Reference column
of the database. This is the usual process of sending SMS from a database
Figure 1 - Sending SMS from a database with Database user
But if the user did not received the message after some time for any reason
(for example the handset is off), then it is possible to cancel the message
from the SMSC with the help of cancel_sm service. It can be the proper solution
if the message has been expired after a definite time.
To cancel the message from the SMSC, insert a record into the database:
Message type: SMS:CANCEL
Recipient: the original recipient of the message
Message: the received callback ID
So if you insert the record above into the database, the Database user will poll
out it and send a cancel indication to the SMSC and the SMSC will return a
confirmation if the message has been canceled (Figure 2).
Figure 1 - Canceling SMS with cancel_sm
First start Ozeki NG SMS Gateway and go to Database user
configuration pane. In SQL Settings menu select SQL for sending
tab. Click on Sent tab and type reference='$callbackid' after
"status='sent'," (Figure 3).
Figure 3 - Type reference='$callbackid'
In our example I send out a test message to demonstrate the
solution (Figure 4).
Message: Hello World!
Figure 4 - Send out a message
On Figure 5 you can see that the message is accepted for
delivery and the callback ID is also defined in this report.
Figure 5 - Callback ID
With SELECT * FROM ozekimessageout; statement you can
query the messages from ozekimessageout table. After clicking on Execute
you can see the message data that contain the callback ID among others (Figure
Figure 6 - Query ozekimessageout table
Now I insert a record to be sent out into the database where
Recipient: is the same as in the original message (+06205460691)
Message type: SMS:CANCEL
Status: send (Figure 7).
Figure 7 - Insert a record to send out
In SMPP service provider the following PDUs will be seen: the
first row is the cancel indication for canceling the message. The second row is
the confirmation about the fact that the message has been canceled (Figure 8).
Figure 8 - PDUs for canceling
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