http://en.wikipedia.org/wiki/GSM

http://www.overstock.com/Electronics/Cell-Phones/GSM,/network,/912/cat.html

http://www.dvdoverseas.com/gsm_phones.htm

http://www.myworldphone.com/storeitems.asp?cc=PHONES

http://www.myworldphone.com/storeitems.asp?mc=NOKIA&cc=PHONES

http://www.mobal.com/

http://www.alibaba.com/showroom/GSM_Cell_Phones.html

http://www.puremobile.com/All/Cell-Phones/

http://www.selectgsm.com/

http://bargainoffers.com/catalog/gsm-cell-phone-c-1.html