Model Q2/Q3 Some users want the tracker always keeping socket connection open. The tracker socket connection default is off. There are two ways to keep the socket connection open. 1. Command B03 time interval less than 60 seconds. For example SMS command: B03,50,50 If the time interval great than 60 seconds, the tracker will enter into sleep mode between the interval, and the socket connection will be off. 2. Command S09 for heartbeat interval settings. No matter what's the configured B03 time interval , the users can configure the heartbeat interval for keeping the socket connection open. Normally the hearbeat interval should be less than 60 seconds, but it also depends on the local network specific situations, greater or smaller hearbeat intervals are possible. S09 heartbeat interval SMS command example: 000000,S09,50,50Summary: If the B03 time interval less than 60 seconds, the device always keep the socket connection open. If the B03 time interval over than 60 seconds, need enable the S09 command to keep the sockect connection open.