I have some problems with programming an application that sends raw data using HTTPConnection to a server over GPRS on a Siemens TC45 modem.
First I set the pin successfully and after waiting a time (a few seconds) the GPRS parameter with AT^SJNET. Sometimes this throws an exception and I don't know why. There is no error in syntax.
In the case of no exception is thrown, the AT^MONI command shows "limited service" and extended error output AT+CEER says "no sim inserted".
This behavior is seen often, but not always. Sometimes it works.
Does anyone know what could cause this problem ?
Is it important to give the correct DNS in AT^SJNET or does it even work with a wrong IP ?
Is it necessary to do a GPRS attach explicit after sending the AT^SJNET command ?