All iPhones have GSM, certain models have CDMA as well, such as Verizon and Sprint in the US, KDDI in Japan, China Mobile, and so forth.
(International carriers not accurate
, It could be AU that is CDMA in Japan, not too sure).
To help us hep the OP however, we need to know what carrier he/she is using it on. If AT&T then its just the plain jane GSM model.