Different providers. One provider will use the one that is made for them. The best way I know on how describe it is with the 5100 series phone. 5185i=CDMA 5120=TDMA differnt models are for different carriers. Did that help you???
Ok let me be a little more specific: 3360: TDMA version for use on a TDMA carrier such as AT&T Wireless and Cingular 3390: GSM version for use on a GSM carrier such as Voicestream and Cingular * note that Cingular has mixed GSM and TDMA markets. By the way, I'm trying to decide whether to get the Siemens S46 phone or not for use on AT&T Wireless' Multi-band One rate plan. One of the stores here in suburban Chicago told me they should be receiving the phone by week's end. But then again, the Nokia 6340 GAIT phone is *anticipated* to be released very shortly sometime this month but of course that's still speculation. I guess I could try out the Siemens phone for up to 30 days and see how aggressive of a deal AT&T will offer for me on the phone to jump over.