To send the message issue Ctrl-Z char (0x1A hex). To exit without
sending the message issue ESC char (0x1B hex).
In Text mode, the +CMGS command has the following syntax:
AT+CMGS=<da>[,<toda>]
After command line is terminated with <CR>, the module responds
sending a four-character sequence prompt:
<CR><LF><greater_than><space> (IRA 13, 10, 62, 32)
After this prompt, you can enter text that should be formatted as
follows:
- if current <dcs> (see +CSMP) indicates that GSM03.38 default
alphabet is used and current <fo> (see +CSMP) indicates that
3GPP TS 23.040 TP-User-Data-Header-Indication is not set,
then ME/TA converts the entered text into GSM alphabet,
according to 3GPP TS 27.005, Annex A; backspace can be used
to delete last character and carriage returns can be used; after
every <CR> entered by the user the sequence
<CR><LF><greater_than><space> is sent to the TE.