Our device connects with TCP socket over GPRS to server and periodically sends packets of ~50bytes. The application can receive SMSes to change the parameters etc. So far the packet sending period was always greater than 10 seconds and everything worked OK. When the period was shortened to 1 second, the SMSes were not received anymore. Changing period back to 30 seconds and the missing SMS was sooner or later delivered.
Actually the margin is 5 seconds. Anything shorter, no received SMS. Also, when dial-in voice call with fast period packets, unknown female voice informs ‘the number is not available’. With period > 5 seconds, the incoming rings are detected.
The device is Fastrack Supreme 10 and runs on R74a.
Can this be my provider, OS (WIP), or am I missing some setup?