I can communicate thorugh RS-232 that connects my Fargo Maestro 100 GSM Modem. I can send and receive SMS'es using AT commands perfectly in text format (AT+CMGF=1) but am experiencing problems with PDU format.

I tried all sorts of ways to issue a send (AT+CMGS) with PDU format (AT+CMGF=0). Please help me to realize this. Here is my syntax:

AT+CMGF = 0

My CSCA (Message center number) is,
AT+CSCA?
+CSCA: "+2666000002",145

The desitnation number is:
+26663104703 (+266 is the country code for Lesotho)

Can you discover anything wrong with:
AT+CMGS=23
> 06916266000020A40B916266134007F37F006021819104310004D4F29C0E
<CTRL-Z>

where the sent message is "Test"?. Remember test works fine in Text mode (AT+CMGF=1)

The result is always, +CMS ERROR: 304. I tried everything I know, please help?