If it's to make phonecalls I would get a a Bluetooth speaker. Motorola has on that u can voice respond to hear texts incoming and send outgoing. Voice pickup for phone calls etc. I think most those features has to be android not sure if that speaker Verizon sells it can work as a regular Bluetooth device or it has those extra features like texting too. I would go to the store and ask. It's not a keypad but it's ment for the car.
Hello, there is a Bluetooth keyboard available for the iphone4S. It is made by Boxwave.com and can be bought in Brookstone stores also. It is called the "Keyboard Buddy" case. The keyboard slides out from the bottom of the case. It works very well and there are videos about it on YouTube. When I went from my Palm Pre 2 to the iphone4S (yes, I finally said good-bye to Palm/HP...), I had to have a physical keyboard. The Keyboard Buddy is exactly what I wanted. Hope this helps you out..
That keyboard would be useful for using email, but actually I'm looking for a phone keypad rather than a keyboard for phone use in the car.