SMPP protocol alphabets

[Hamid Yusefzadeh]

Dear kannelers,
I am working on a SMPPv3.4 application. But onething is not clear for me. 
I noticed that SMPP defines just 8 bit and 16 bit alphabets and not 7 bit 
alphabets (is that correct??)
If that is correct, how mobile handsets interact with SMPP applications? 
Should mobile handsets send their information to these applications in 
binary format (I mean 8 bit alphabet)?
Thank you,
Hamid