I am working with SMS Application using VB.NET and Serial Ports using GSM modem. I checked the following threads on this site but it cannot answer my problem. Here's what I've done
AT+CUSD?
+CUSD: 1
OK
AT+CUSD=?
+CUSD: (0-2)
OK
AT+CUSD=1,"*102#",15
ERROR
I also changed the message format to PDU and Text but the result stays the same. It always show Error.
Please help.