无法发送USSD GSM调制解调器

Question

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.

Answer 1

First try this :

AT+CSCS?
mine is like this
+CSCS: "PCCP437"

OK

To know what kind of encoding is used. And to know the supported encoding by your modem do this :

AT+CSCS=?
+CSCS: ("UCS2","GSM","PCCP437","PCDN","IRA","8859-1","HEX","UTF-8")

OK

It will return valid values for encoding. Set it like this :

AT+CSCS="UCS2"
OK

Now your command will be like this using UCS-2 encoding :

AT+CUSD=1,"002A0031003000320023",15

Tell what you find?