 Ringtones and graphics contain binary data and Nokia's SCKL encoding provides a method of delivering binary data to a phone using only printable characters.Thus it allows ringtones and graphics to be delivered over CDMA, iDEN and TDMA networks.Clearly it also requires a phone that can correctly interpret the SCKL format and most Nokia phones can do this, as well as some phones from other manufacturers and many WAP compatible phones.