Can the iphone work with any portable player?

I got to the P23-speakers portable player Roxy from the storage b4 of the apple iphone came out and I thought that worked together but it doen 'T.I' from the VE bought a mercury too. On apple Says w / ipods compatible but not the iphone. Yet is there anyway to get to arround that? The measures and then it reads the groove "comp" of the device, so I tried the dbl I parteggiato cables aus. male. Still nothing. So I guess the 'the m. Once that question if there is something out there I can buy to put the speakers on my iphone that 'portable St. Thank you.