I have a 99 SLK230. No phone was installed. Is there a bluetooth adapter for the radio/phone?

 

I use a BlueAnt Supertooth II phone handsfree kit in my 1998 SLK230. Fits on the sun visor and works just fine. Batteries need infrequent charging and last for ages so no need to plug into the cigarette lighter and no cable dangling from the visor. See http://www.myblueant.com/ for USA dealers.