Yep,I'm using Campus Component SIM 900 module,here is the link to it.
http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCcQFjAA&url=http%3A%2F%2Fwww.campuscomponent.com%2Fmedia%2Fdownload%2FGSM%2520Module.pdf&ei=0wpYU-6iPIz7rAfBmoDgAg&usg=AFQjCNGGvkmOPTBvb-l_Gj762M4KmwVloA&bvm=bv.65177938,d.bmk