Solution to your proble

Same problem face me too today
and I solved it like this :
first if your mobile support Hex mode
(you can know by writting : AT+CSCS=? )

then make the mode Hex as follows:
AT+CSCS="HEX"
then execute this command :
AT+CSMP=17,167, 0,8

now you are ready to send the arabic message but after u make some encoding
for example...