I've only used a Traffic unit in Brisbane as there is no signal here - for Garmin anyway - there's nothing to set up, the unit just receives info about road conditions and alerts to do a detour or such. We were not there long and never noticed any alerts. "Traffic information is updated constantly, and map updates are available for download up to 4 times a year. Both features are ready to go, right out of the box, with no subscription or update fees and no expiration dates."
The GTM 25
traffic receiver uses a separate cable moulded to the power cable which is not the most elegant solution at all, making it about 9mm x 3mm with an in-line "black box" (65 x 19 x 12). A normal 3mm circular 12 volt to USB power cable could be used if Traffic was not required.