Globalstar Product Management – Technical Support

SMS Retry Schedule

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An SMS message can be sent to a Globalstar device through a variety of paths, including several different email addresses, a web page, and through automated communication with our http SMS front end server.

When the SMS is initially delivered to the SMSC (Short Message Service Center), the SMSC determines if the Globalstar device is powered on, registered, and ready to receive SMS messages.

Device Ready:

If the device is ready, the SMSC attempts delivery of the SMS message to the Globalstar device. If the SMSDelivery (to the active unit) fails for any of the queued SMS messages, the SMSC uses the following “retry” schedule to attempt to deliver the message to the Globalstar device.  It will keep trying as long as the unit is active.

The current SMS retry schedule is…

       1m:2m:3m:5m:5m:5m:15m:15m:30m:30m:1h

       … which means;

       retry after 1 minute,
       then two minutes after that,
       then 3 minutes after that,
       then 5 minutes after that,
       etc…until the above schedule is exhausted,

       the last element (i.e. 1hour) is repeated after that.

At each of these retry intervals, the SMSC first determines if the unit is registered and available.  If the unit is ready, the SMSC tries to deliver the message and, if the SMSDelivery fails, the SMSC goes to the next increment in the above “retry schedule”.  As soon as an SMSDelivery is successful, the SMSC will deliver all of the messages in its queue for that device.

Device Not Ready:

If the SMSC ever finds that the Globalstar device is inactive (not registered), the retry schedule is NOT implemented and any pending retry activities are halted.  Instead of wasting resources trying to send to a message to a unit that is inactive, the Globalstar system sets a “Delivery Pending Flag” for that Globalstar device.  The system immediately alerts the SMSC the next time that the Globalstar device registers, and the SMSC then attempts an SMSDelivery, per the “Device Ready” discussion in the preceding section of this technical note. 

How to Trigger the SMSC to Send All Pending SMS Messages:

As soon as the SMSC receives a new SMS message for a device, the retry algorithm begins all over again. Therefore, if you wanted to power up a Globalstar device only once a day and immediately collect any messages that had been previously queued to the unit, all you would need to do would be to send an SMS to the device right after it was powered. The SMSC would receive the newest message, would be able to deliver the message, and would then send all the queued messages.

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Written by Joseph Crowley

August 9, 2008 at 9:06 pm

Posted in SMS

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