+CMS ERROR 305

Hello everybody,

I’m using a fastrack xtend modem used to send sms.
I Send this AT commands:
AT+CMGF=1
AT+CMGS=“The phone number”

The message
CTRLZ
and sometime I got an error +CMS ERROR 305 after the Ctrlz
This errors appends not always even if I send the same text…

Anyone have an Idea about what to do ?

You can refer to AT command guide to find the meaning of this error ,it would be given in the appendix section.This error means invalid text mode parameter.May be you are trying to send a PDU mode message without activating the PDU mode.