I developed a Java application, which through a 3G modem I get the SMS’s received. The problem is that several users to send SMS to this same number (about 25, 30 users). I noticed that the receipt of SMS’s occurs intermittently. Sometimes all are received, sometimes only a few are received and/or others arrive several minutes later. There isn’t a rule.
Does anyone have more knowledge about this behavior of the cell phone operators?
This can be a limitation of the operators, or a burden upon my modem?
Your 3G Modem is connected to an SMSC (Short Message Service Center) of your operator. This in turn is connected to other SMSC’s across the world (sometimes called the SS7 cloud). SMS messages from other mobile devices can take many different routes depending on how their mobile operator interconnects with yours. This can be due to price, mobile operator agreements and a million other factors. For example a cheaper route could involve multiple hops (between SMSC’s) through multiple countries. Also as your operator will have a queue of messages to send to your device and depending on traffic can result in rather unpredictable delivery times. Finally your 3G modem also has limitations on how many SMS’s it can handle depending on how it’s firmware is programmed.
That’s a very top level overview of some of the influences of SMS delivery times. Hope this helps.