+cmgs fails at ctrl-z in text mode

Dear All

I need advise on a problem with +cmgs via hyperterminal.
Basically everything seems fine but at the last ctrl-z it gives an
error.

The phone (in Sri Lanka) is able to send and receive normal SMS
messages punched on the phone keypad.
The sequence of at commands follows.


at+cgmm
LG-G5400 GSM Mobile Station

OK
at+csms=?
+CSMS: (0,128)

OK
at+cmgf=?
+CMGF: (0-1)

OK
at+cmgf=1
OK
at+csca?
+CSCA: "+9477000003",145

OK
at+cmgs="0777808439"
> testing one (This line was terminated with ctrlz on the keyboard)
ERROR
at+ceer
+CEER: No cause was given


Any advice would be much appreciated
Many thanks indeed for your time.

Chris