cell phone choice

I'm wondering if anyone has advice about cellphone selection in US. The MB website info is "Your Mercedes-Benz dealer offers a selection of the latest Motorola mobile phones for most major carriers." Is there a choice of 1 of several Motorola phones or is it just dependent on the carrier. I didn't have a choice for my wife's E320 2 years ago but a lot has changed including some manufactureres with bluetooth compatible connections which seems more innovative. The salesperson wasn't very knowledgable about this nor was he able to find the windscreen through his parts department although it's listed on the website. As an aside, I was disappointed that MB dropped the voice recognition feature which seems to me to be a step backwards.