What is needed to receive live traffic?

My question is more related to gps devices rather than softwares. What do I need to have in the gps device to receive live traffic? I see that lots of the devices have fm transmitter which can be used to transmit sound to the car's stereo and I presume by the name that it can't be used to receive any signal. What specification should I look for to buy a new gps? I'm not looking for any brand names but rather a generic ones made in china, preferably with bluetooth, 5-7" screen and at least 4gb capacity. Thanks!

In order to receive "live traffic", it depends what you mean by that. A unit with a TMC receiver will (MAY, depending where you are) be able to receive various alerts as to road conditions and depending what GPS software you use, use this info (which is piggy-backed on FM station broadcasts) to either alert you as you drive, or to automatically modify your route. This has nothing to do with "FM Transmitter"...that's a whole different thing that broadcasts any sounds that the unit makes to a chosen frequency that you tune to on your in-car FM stereo.
Other "Live traffic" may be available if the unit has a way to keep an internet connection (by WiFi, etc), but this is very rare in a stand alone GPS unit.

Thanks for your response! I couldn't find any generic gps with tmc but there are quite a few tmc receivers, especially from tomtom that can be added to tomtom gps receiver. I was wondering if any of those tomtom receivers would work with my Omnitech gps running Primo 2.0 in North America.

indijones wrote: I was wondering if any of those tomtom receivers would work with my Omnitech gps running Primo 2.0 in North America.

I know of only one that will work with the Omnitech. Royaltek rta-3000 usb. However if you live in NA, this will only "allow" you to receive the boadcast. All TMC in NA is subscription based. If you don't have paid license...it still will not work.

Thanks! That's too bad for NA. Wish it could be free just like Europe. So, no point in looking for tmc :(